The presser foot doesn't sit all the way down in order to sew correctly. Can I adjust it myself? How?

It is unlikely that you needed to go very far with the tear down. You are brave. Put it back together and take it in for servicing.

Why is my presser foot lever loose?
The presser foot lever is very loose and not moving the bar (foot lever). There is probably either an adjustment not set correctly or a screw that needs adjusting or replacing.

White Sewing Machine Presser Foot Lever Is Loose? ' ThriftyFun

Adjust the pressure foot setting. The basic setting is 50

Hi,
Try taking your presser foot off and lower the presser foot lever. Does the error code go away? The machine won't sew without the presser foot to hold the fabric down, but without threading the needle, will the machine run without the presser foot? Now try the standard presser foot (usually J ) and if you get the error code then the sensor at the top of the presser foot assembly is out of adjustment. Without knowing more about your machine this is all I can suggest.
Good luck,
Bob

Could be the presser foot pressure is set too light. Also, the presser foot bar may need adjustment.

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Not sure what you mean by foot "rest." If it is presser foot, then you may not have the correct presser foot for your machine (basically, there are 3 types--low shank, high shank, & slant shank). Usually, there is also a pressure adjustment for the presser foot that increases the amount of pressure applied to the fabric and feed dogs. Consult your owner manual. Pressure adjustment is usually either a dial, a plunger type on the top left of the machine (pushing down increases the pressure--push down on the outer ring to release it), or a screw at the very top of the presser foot bar (sometimes under the top lid).

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Yes indeed, it is possible--sounds to me like a screw worked itself loose. However, I would purchase the service manual for your machine. As a bonus, it tells you how to make all kinds of useful adjustments.

Go to Sewing Parts Online and do a search under Singer Service Manuals; if they don't have it in stock, call or email them and they will be happy to order it for you. Generally takes two weeks to get it in stock.

HAVE THE 6091 MACHINE AND THE FOOT IS NOT FROZEN BUT WON'T GO DOWN. OILING THE MACHINE DID NOT HELP AT ALL. HAD A REPAIR MAN COME TO THE HOME AND CLEAN THE MACHINE. STILL THE FOOT WILL NOT GO DOWN.

The presser bar may be stuck and may need some WD40 on the top so it seeps down the needle bar, or the presser foot dial or adjuster is set to 0, or the presser bar spring has broken, or the block and screw on the presser bar where the lever is has come loose.

Are the feed dogs up and working?

Is the presser foot down?

There should be an adjustment somewhere on the top of the sewing machine, above the presser foot where you can adjust the pressure of the presser foot - left for less and right for more.

Is the fabric under the presser foot when you begin sewing?

Remove the thread from the machine and rethread it . Raise the presser foot before you pass the thread through the tension assembly. Do a tension test.
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(To do this test, adjust your tension setting to normal or medium or 5 or something in the middle. Raise the presser foot and pull the thread through the tension. It should pull easily!! Lower the presser foot and pull the thread. It should pull noticeably harder.)
If it doesn’t work this way then you probably have a piece of thread or lint stuck inside the tension discs. To remove it, turn the tension to 0 zero and raise the presser foot.Using a small screwdriver, open the space between the discs and spray with canned or compressed air. The stuff should come out. Do the tension test again to make sure you got everything and then try sewing again.
Normally, what you are describing is a threading problem or a tension problem.
sewman7