Hi all, lurker here.
I recently acquired a Singer 136w110 post-bed machine. After many tries stitching 69 poly thread, I switched to the nylon thread that worked fine in my Adler 67. I got the hook timed correctly, needle seems to be correctly aligned with the hook now and it's finally stitching. Only problem is that now the tension is out of whack. I'm new to sewing machines in general which is why my search failed to turn up any solutions since I probably don't have the right terms.
The issue is that the bottom tension is way too tight. I have the upper tension cranked all the way down but I'm still seeing a straight line on the bottom on the test piece (5oz oil tanned, 1 layer). I played around with the screw on the bobbin case but that doesn't seem to do anything. The problem is when the bobbin and case are in the machine, it seems like the little spring loaded lever that holds it in place is clamping down too much preventing the bobbin from turning freely.
When I pull on the bobbin thread here, it spins freely
Now with the lever down, when I pull on the bobbin thread it's very hard.
I'm going to try using a fine grit sandpaper to smooth out the bottom of the bobbin case even though I don't see any obvious burrs. Is there any way to adjust the tension on that lever?