Update: my $12 thrift store sewing machine jammed on stitch 400 and I fixed it with a bent paperclip
Picked up a beat up Singer at the Goodwill on Devon Ave for 12 bucks and it ran fine for a few weeks, then the bobbin thread started bunching up every single stitch. I popped open the plate, found a wad of lint and a bent needle, and straightened a paperclip to fish out the gunk since I don't own a tiny brush. Runs smooth now and I've hemmed 6 pairs of thrifted jeans with it. Anybody got a cheap trick for keeping tension right on these old machines?