Originally Posted by
Whigrose
...My hunch is at some point the upper thread tension dial was removed and not properly seated back on since I have been fiddling quite a bit between 5 3/4 isn to 7....
You don't say which color is the bobbin thread and which color is the top thread.
Since you have a hunch, have you taken it apart, cleaned and reassembled the tension assembly? There are a couple of threads here on QB about the 15-91 tensions. This one has links that no longer work -
tension trouble singer model 15-91 but see particularly post #7.
Here is another one with pictures and the link (in post #2) should work
15-91 tension assembly question. Also read #4 as OP described what the problem was.
There are a couple videos specifically for the 15-91 and then there is the one linked to above, about older tension units, but for a different machine.
https://www.youtube.com/watch?v=Gz-rffxY_6w
https://www.youtube.com/watch?v=QCcKzpeiVLI
https://www.youtube.com/watch?v=guYToL6Gegs
Also did you make sure the bobbin area was cleaned out and no thread caught. Another thing is that has been known to cause some problems is that the area under the spring may have thread caught in it or possibly a thread groove or burr on the bobbin case. I really don't think that is the problem.
Janey - Neat people never make the exciting discoveries I do.
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