the bottom thread stays straight on my 1980 kenmore machine, I have had it cleaned and repaired several times without it staying more than a few stitches.

Cilla, April 2007

If the thread lays flat on the bottom it is usually the top tension that is loose. When threading the top tension with the presser foot UP go as far as just before threading the needle.
Testing upper tension:
Now, put the presser foot DOWN and gently pull on the thread. If you have resistance that means the upper tension is probably fine. Raising the presser foot and there should be little to no resistance.
If there is about the same resistance with the presser foot up as down I suggest taking a small piece of material and putting it between the tension metal discs. Perhaps a bit of lint is in there preventing the disks from seating on the thread properly.
If everything seems ok try increasing the tension to a higher number. Good luck

Jim T, May 2007

Hello Cilla,
I should have asked, when you say the thread is staying straight on the bottom of the machine, is the machine actually sewing stitches properly or is the machine not making stitches at all ?
Ken

Ken dourof, April 2007

Hello Cilla,
Either you have the bobbin in the wrong way round which means there is no tension, if you have not done anything to the bobbin case itself that is most likely to be the problem on the bottom.
Or, you may have threaded the machine and not made sure the thread has gone between the tension discs, remember to thread the machine with the presser foot up, or, you may have the top tension set too low, round about number 5 is about normal but it will depend on the type of thread, if any of these do not cure the problem get back to me again and I will tell you how to adjust the bobbin case but go for the simple things first.
Ken
drivewithken@blueyonder.co.uk

Ken Dourof, April 2007