I just aquired a beautiful 1974 Singer Sylist, complete with case and manual. I’ve never really owned a sewing machine before, and I am very excited, but also very clueless.
I’m pretty sure I have everything threaded right, but every time I sew, I end up with a huge knotted mass on the bottom of the fabric and eventually the thread breaks. What am I doing wrong?
Once you’ve got everything threaded, and ready to go anew, place your workpiece under the presser foot and then turn the knob on the back (there should be an arrow to tell you which way) until the needle pushes down through the fabric, and then comes back up. The thread through the needle should have pulled up a loop of thread from the lower bobbin. If it did, use a needle or something to pull the loop until the end pulls through. You should now have the two ends separated on top of the fabric. Now turn the knob through a couple turns to lay down two or three stiches manually. At that point you should be able to step on the pedal and run off your stitch. If your needle isn’t catching the the lower bobbin properly, or it’s still tangling after you do this procedure, you might have misthreaded sowmting, or the tension needs to be adjusted.
Look in the manual, there should be a page which explains “tension”. There must be tension from the top (needle) and bottom (bobbin). Your tension is wrong if you get: knotted thread from either the top or the bottom.
Thickness of fabric changes the tension you need. Always start with a swatch of the fabric you’re working on to make sure you get the right balance.
Happy sewing !!
IANA sewing machine expert. In fact my biggest accomplishment with one was on my grandmothers machine which had a foot treadle, I managed to drive the needle through my thumb. :eek:
However, I did a google and found this:
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If that doesn’t help google with “sewing machine, problems, thread knotting”. There were other hits that might help. 
Has it been in for a tune-up? If you got it at a garage sale or out of an attic, it probably needs a little help. Take it into a sewing machine shop for a workover, and see if that doesn’t help…the person may well be willing to give you a little lesson on running the thing.
When my cranky machine knots on the bottom of the piece, it is usually caused by a tension problem in the top thread. I second the tension adjustments (psrticularly the top thread).