E99670 short shank, or snap on presser feet?

Using Standard Low Shank Feet
There are 2 different adaptors available that will allow you to use standard low shank presser feet and snap on feet. Some people prefer this method instead of forking out $20-$50 per Bernina presser foot. If you have other sewing machines, it may make sense financially to invest in more low shank or snap on feet that you can take from machine to machine. If you decide to go this route, I just want to remind you that if your machine uses the presser feet with the sensors, these adaptors will not trigger those sensors.
Use Snap On Presser Feet
This snap on presser foot adaptor is available in both old style and new style. When ordering your generic snap on feet for this shank adaptor, be sure you're ordering the correct maximum stitch width that your machine has. This is a very convenient shank since you're able to quickly switch between many different feet without having to remove the shank.
Use Low Shank Presser Feet
Chances are if you sew, you have low shank feet laying around (or 40). This low shank presser foot adaptor is available in both old styleand new style. Simply install this shank like a normal Bernina foot, and then screw your low shank foot to the shank. If you install a low shank foot onto this adaptor, be sure to test with a wide zig zag to make sure the installed foot is wide enough to accommodate your machines maximum stitch width.

It is most likely the presser foot you are trying to install was not made for your machine. There are so many machines available and most of those machines have their own presser feet, which are not interchangeable. Unfortunately, even a Singer presser foot is not interchangeable with other Singers. Some have screw attachments, others have lever attachments, some have long shanks, others have short, some are straight, others are slanted. You need to figure out what style presser foot your machine takes and then search for either the presser feet that fit or a shank adapter that you can then use snap-on feet (kits are available on eBay).

http://www.sewingpartsonline.com/sewing-machine-presser-feet.aspx

Sewing Machine Feet eBay

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Check to be sure you are using needles and thread that are compatible with the fabric. Generally, finer threads will work better on fine fabrics along with a smaller needle. Be sure to change needles frequently as dull, bent, or nicked needles will cause very frustrating issues.
All About Needles

Remove the thread completely from the machine. RAISE the presser foot and rethread from the beginning, making sure the thread path is correct.

Some machines have a presser foot pressure adjustment (consult the owner's manual). Adjusting the pressure that the presser foot applies to the fabric & feed dogs is helpful when sewing especially fine or heavy fabric. Also, when sewing fine fabrics, loosening the tension could be beneficial.

Changing presser feet may also help, ie try using a straight stitch foot vs a presser foot for zig-zag stitching.

Something else you can try is finding a presser foot with a teflon finish or a roller foot that will glide or roll with the fabric through the machine. Even if you can't find a brand name presser foot for your particular machine, an adapter shank can probably be found that would allow you to use snap-on feet of all different designs and uses. Provides a lot of choices for presser feet for less than purchasing a brand-name presser foot. There are snap-on kits available on eBay and other auction sites.

Some machines also can take a straight-stitch needle plate--usually an additional accessory that can be purchased. The hole where the needle penetrates the needle plate to access the bobbin thread is actually a small round hole. With a zig-zag needle plate, the hole the needle penetrates is a wide rectangular hole that can allow fine fabrics to be pulled down through the hole. Zig-zag capable machines usually have a zig-zag needle plate as standard.

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You first need to determine which shank the presser foot uses on your machine. You can compare your shank (current presser foot) with these photos to see which one your machine uses.

http://www.sewingpartsonline.com/sewing-machine-presser-feet.aspx

NOTE: If you purchase a snap-on presser foot, you will also have to buy a "shank adapter" that will attach the presser foot to the needlebar. Here are some pictures of snap-on adapters:
Kenmore sewing machine snap on adapter Google Search
However, you will still need to make sure to buy the correct adapter for your machine. The GREAT thing about buying a snap-on adapter is you can add a lot of presser feet to your sewing machine accessories because you can purchase additional snap-on presser feet or even a complete set of snap-on feet that will all work with your adapter and your machine!!!
Kenmore Presser Feet eBay
You will just snap one foot off and snap another on!!! Great idea!!!

OR--you can take your current presser foot along with the make & model of your machine and check with the local sewing repair shops to see if they have what you need.

FYI, once you know what shank your machine has, you can probably also find other specialty feet for your machine, ie walking foot, free-motion foot, etc.

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If you can buy an adapter shank for your machine, you can then purchase a generic snap-on zipper foot.
Sewing machine feet Super high shank high shank slant shank low shank snap...

This is posted in the UK, but you should be able to find something similar in the US:
Toyota 2260 Sewing Machine Feet Bobbins Needles Parts

Stitchery Sewing Machine Attachments Needle and Thread

http://www.sewingpartsonline.com/sewing-machine-presser-feet.aspx

Presser Feet Snap on and Screw on for Sewing Embroidery and Serger Machines

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here's some links,, check to see if any of these are the one you
need
http://www.ebay.com/itm/Patchwork-Presser-Foot-Feet-for-Janome-Sewing-Machine-/160647143501?pt=LH_DefaultDomain_0&hash=item256750e04d

http://www.ebay.com/itm/15Pcs-Domestic-Sewing-Machine-Foot-Feet-Presser-For-Brother-Janome-Toyota-Singer-/160873840950?pt=LH_DefaultDomain_0&hash=item2574d40136

http://www.ebay.com/itm/Teflon-Roller-Presser-Foot-for-Janome-Sewing-Machine-/150658389742?pt=LH_DefaultDomain_0&hash=item2313f096ee

http://www.ebay.com/itm/Little-Presser-Foot-Feet-for-Janome-Sewing-Machine-/150658376074?pt=LH_DefaultDomain_0&hash=item2313f0618a

http://www.ebay.com/itm/LOW-SHANK-ZIG-ZAG-Presser-FOOT-Elna-Viking-Pfaff-Brother-Janome-Kenmore-Singer-/170890014355?pt=LH_DefaultDomain_0&hash=item27c9d6ae93

http://www.ebay.com/itm/Snap-on-1-4-STRAIGHT-STITCH-PRESSER-FOOT-for-JANOME-/250740380263?pt=LH_DefaultDomain_0&hash=item3a614a9267

http://www.ebay.com/itm/Standard-1-4-Straight-Stitch-Presser-Foot-for-Janome-/150658382783?pt=LH_DefaultDomain_0&hash=item2313f07bbf

http://www.ebay.com/itm/Open-Toe-Presser-Foot-Feet-for-Janome-Sewing-Machine-/150658371125?pt=LH_DefaultDomain_0&hash=item2313f04e35

http://www.ebay.com/itm/1-4-Straight-Stitch-Teflon-Presser-Foot-for-Janome-/150658967978?pt=LH_DefaultDomain_0&hash=item2313f969aa

http://www.ebay.com/itm/Teflon-Presser-Foot-Feet-for-Janome-Sewing-Machine-/150658374627?pt=LH_DefaultDomain_0&hash=item2313f05be3

You should be able to figure out which shank your machine has here:

http://www.sewingpartsonline.com/sewing-machine-presser-feet.aspx

If you have the manual, it should show you how to change the presser feet.

SINGER Instruction Manual pdf model 628

If your machine and presser foot look like the one in the video, the screw on the left side of the presser foot should be what holds the presser foot in place.
Singer Touch and Sew Threading and Bobbin Winding

There may be other videos here that would be helpful.

I would suggest that you try http://www.sewingpartsonline.com/zig-zag-foot-standard-low-shank.aspx the page shows this foot as being suitable for your machine.

Many low shank sewing machine feet are interchangeable.

a generic low shank Zipper foot is also there http://www.sewingpartsonline.com/zipper-presser-foot-low-shank-55411.aspx

Trust that this helps you.

I would suggest that you try http://www.sewingpartsonline.com/zig-zag-foot-standard-low-shank.aspx the page shows this foot as being suitable for your machine.

Many low shank sewing machine feet are interchangeable.

a generic low shank Zipper foot is also there http://www.sewingpartsonline.com/zipper-presser-foot-low-shank-55411.aspx

Trust that this helps you.

Make sure you get a foot designed for this Singer sewing machine. Then for snap-on feet, push down slightly on the front of the foot then pull forward (with some you pull to the left). To insert a new foot, push the foot towards the connector (back or to the right) and then push the back of the foot up (once in contact with the connector) while still moving into the connector. (You should feel the spring lift up and snap around the foot.)

For shanked feet, loosen the thumbscrew and slide the open side over the screw and press against the shaft. Then tighten the thumbscrew.

I hope this helps.

Cindy Wells
(my older Singer uses a snap-on zig-zag foot. This foot gets pushed in from the front . Keep the foot below the shank until you have the bars centered around the base of the shank. Then bring the foot up and push back until it snaps into place. There is a horizontal rod between the bars and the shanks locks around that rod. The rest of the feet are shanked.)