The top thread keeps breaking. The thread pulls tight and breaks. I have removed a broken thread piece from the upper take-up lever, rethreaded (several times), cleaned out bobbin, moved thread spool on machine. Still breaks thread.

thread is not between tension plates but behind one

Possibly the top tension is too tight. It is pulling the bobbin thread to the top, but could also be so tight that it is eventually breaking the thread. The top thread could also be threaded incorrectly so it is not feeding out like it should.

Remove the top thread from the machine.
ALWAYS RAISE the presser foot and rethread from the beginning.
Set the top tension to the midway point.
Test your stitch. Tweak the top tension until the top and bobbin threads meet in the middle of the fabric.

Ooh, boy. You are having some problems.

First thing I suggest:
Remove the top thread from the machine.
Install a brand new needle.
ALWAYS RAISE the presser foot and rethread the machine from the beginning.
Verify the thread path is correct.
Remove the bobbin case & check that the bobbin is loaded (turning) the correct direction and the thread is threaded through the bobbin tension.
Set the top tension to the midway point--this can be tweaked later.

Also, you might try changing the brand/type of thread you are using. AVOID old or bargain bin threads!

Confirm that you are using the correct needle size & type for the fabric you are stitching, ie ball point needle for knits, size 70 needle for light-weight fabrics like chiffon, silk. Be sure that the thread is not too big (or too small) for the needle eye.

Breaking thread could result from several things, ie tension too tight, the thread is too large for the needle eye, the fabric is too coarse or tightly woven (try a top stitch needle). or there could be a burr or rough spot somewhere in the thread path that is snagging and breaking the thread.

All About Needles

For the thread jumping out of the take-up lever, this occurs on a lot of older machines but I wouldn't think it likely on yours. Makes me think there is something holding back the top thread. If you rethreaded (as described above), it may have taken care of this problem. On older machines, I've actually resorted to folding a piece of tape over the opening in the take-up lever so the hole is closed and the thread can no longer escape.

There could also be some gunk or broken thread stuck in the tension disk. If you continue having problems, try soaking a length of cotton perl thread with alcohol (wring out the excess). Then with the top thread removed from the machine, RAISE the presser foot, loosen the top tension all the way, and gently pull the length of perl cotton DOWN through the tension disk a few times. This may remove any gunk or thread that may be stuck.

First check your thread. How old is it and has it been exposed to heat and sun? Try to break a piece off. If it breaks easily it is rotted.
If OK then completely rethread your machine. the thread can get looped over a lever and you cant see it until you take it all out.
Check your upper tension, be sure it is not too tight .
Last, try another thread and see if it makes a difference.

Sounds like your tensions, both upper and lower are out of whack. Easily fixed if so...google a vidyfor your make/model machine on adjusting both upper and lower tensions.

Totally remove the upper thread from the machine then rethread. When threading the top thread, ALWAYS RAISE the presser foot so the thread will seat properly in the tension disk. The thread is probably breaking because the tension is too tight. Try setting it at the midway point and then tweak it from there. Also check that the thread path is correct--incorrect threading could cause extra tension on the thread.

In case there is gunk build-up in the tension disk, you can moisten a piece of perl cotton thread with rubbing alcohol, loosen the tension disk all the way, Raise the presser foot and then, gently, pull the perl cotton Down through the tension disk a couple of times. (Always pull Down, Never Up!)

If you continue to have problems, you may need to take it for service.

If the top thread sews a few inches and then breaks, something is catching the top thread and holding it until it breaks. Usually, this will happen when using the old style thread cones with the slit in the edge to keep the thread from raveling off the spool. To prevent the thread from hanging up, turn the thread spool over so the slit is at the top instead of the bottom. Sometimes top thread breaks will happen if the thread becomes looped around the thread spool pin.

Remove the thread, ALWAYS RAISE the presser foot and then rethread the upper thread. Verify that the thread path is correct and that the thread has not looped around a guide.

If the thread is fraying at the needle eye, the needle/thread are not compatible. Also, the tension may be too high.

Check that the upper tension disk is clean--no gunk buildup or thread pieces stuck.

If the thread is actually breaking when it penetrates the needle plate hole, there may be a burr or nick somewhere below that is catching the upper thread. You can wrap your finger with a piece of fine fabric, like an old pair of hosier, fine knit fabric, etc. and running your finger around in the bobbin area, under the needle plate. If you get snags, then you have a burr or nick. If it is small, you can sometimes smooth it with a fine emery board. If it is a large burr, you may need to purchase a replacement part.


Why Does My Top Thread Keep Breaking Sewing Machine

Sewing Machine Problem 1 Thread Breakage

Sewing Machine Thread Keeps Breaking

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try a new needles
check for burrs
make sure the thread is not caught anywhere

Remove all the thread. Loosen the upper tension as far as it can go and gently pull a length of UNwaxed thread or pearl cotton down through the tension disks to remove anything that may be stuck. Check that the needle has been installed facing the correct direction and that it has been inserted all the way up before the screw is tightened. Clean the bobbin area of any dirt, lint, or threads. RAISE the presser foot BEFORE threading the upper thread. This allows the thread to seat properly. Re-thread from the beginning. Set the upper tension to the midpoint and test.

If it is still happening, then try installing a brand-new needle (the one you have may be damaged or defective). If the thread is shredding before it breaks, then there may be a needle compatibility issue.

Why Does My Sewing Machine Top Thread Keep Breaking Howcast

All About Needles

There are several things that can cause the top thread to break. Tight tension on the bobbin thread could be a problem, but you may have a different issue if the thread is catching in the bobbin case.

Something worth trying: install a brand new needle. Remove all the thread from the machine, ALWAYS RAISE the presser foot, and rethread the top thread from the beginning. Confirm the thread path is correct. Also, rethread the bobbin case and verify the bobbin is turning the correct direction in the bobbin case. Also, try a different type of thread (AVOID old or bargain bin thread.)

Why does the upper thread keep breaking Brother

Why is my thread breaking

Sewing Machine Problem 1 Thread Breakage

One more thing. You mentioned it is a vintage machine. Has it been thoroughly cleaned and oiled recently? These old mechanicals need frequent and regular TLC to keep them purring. It could be the bobbin area needs fresh oil to keep it rotating smoothly.

Wheel on right side that controls the needle up and down is very tight...