On old singer sewing machines, how do you sew on thicker fabrics? I s it a matter of loosing the foot or the thread tension? My machine is so old it doesn’t have a back stitching mechanism! It’s black with old colorful designs painted on it. I do not see a number anywhere but if you can tell me which knob or place it needs to be adjusted I think I can figure it out! Thank you, kathy

You can't adjust the presser foot force on the 7033. The loose loops indicate the top thread tension is too low. Try re-doing the top thread with the needle and presser foot fully up. Next make sure that the area under the bobbin case is clean. If you are still having an issue, consider a walking foot to keep the fabric layers together. Make sure to get one for a slant shank sewing machine.

I hope this helps.

Cindy Wells

Install a brand new needle (make sure it is compatible with the thread and fabric). Remove the top thread from the machine. ALWAYS RAISE the presser foot and rethread from the beginning. Verify the thread path is correct. Set the top tension to the midway point and retest your machine. Tweak the top tension until the top and bobbin threads meet in the middle of the fabric.

AVOID old or bargain bin thread.

http://www.servicethread.com/blog/stop-industrial-sewing-thread-breaks

Sewing Machine Thread Keeps Breaking

https://www.sewhere.com/why-is-my-thread-breaking-how-to-avoid-thread-breakage-at-your-sewing-machine

Why is my thread breaking

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Are you saying the upper thread is knotting under the fabric as it stitches? This is bird nesting or thread nesting and is generally caused by mis-threading, the thread not being seated in the tension disk, or the upper tension too loose.

When threading the upper thread, ALWAYS RAISE the presser foot. Verify that the machine is threaded correctly. If one guide is missed, the stitching will go haywire. Start out with the upper tension set around the midway point and then tweak it through test stitching.

What causes Bird Nests Superior Threads

Sewing Machine Thread Bunching Up Here Why

Birds nest under the fabric big loops of thread top side looks good...

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try this link.
sewing machine computer stuck Google Search
or this one.
My needle is only sewing in place the feed dog is Google Search

Insert a new needle, (flat side facing rear of machine), now totally rethread. Try this, with presser foot up, pull top thread, it should pull smoothly, now lower presser foot, the thread should barely move. This should seat the thread in the tension discs. If that doesn't work, call Singer at 1-800-4singer.

Always thread a sewing machine with the presser foot up and this will eliminate what looks like a loopy bobbin thread.

If you thread with the presser foot down, the tension control is not open to accept the thread as it is designed to do.

Then when you sew, the tension cannot control the top thread and the bobbin thread pulls the loose top thread to the bottom of the fabric.

Normal setting for the tension is usually mid-range ( 4 or 5).

Make sure to thread the machine with the presser foot up to insure the thread is seated into the tension control.

Always free-motion with the presser foot down.

Try a lower setting on the tension.

Make sure that there is tension on the thread when you have passed it through the tension unit, by making sure the presser foot is down, and then gently pulling the thread to feel tension. If there is no tension, as seems to be the case, check the tension discs inside the unit to make sure that there is no debris stopping them from closing.

Unthread your machine and set the tension to 4.5. rethread your machine up to the needle and then put the presser foot down. If the thread pulls hard, your machine is threaded right if it pulls easily, the thread is not thru the tension wheel correctly.

Rule of thumb:: loops on the top, problem on the bottom.
loops on the bottom, problem on the top.

hi there
raise pressure foot up thread making sure thread passes between thread guide this should solve problem never alter bobbin tension,
mary h