Sunflowerzz, I had read so many peoples' bad experiences of disassembling the tension unit that I was really leery of messing with it. I took it apart carefully following the book and cleaned all pieces. None were terribly grungy but all are nice and shiny now. Didn't notice any burrs or rough places on the interior pieces.First try at getting it back together didn't go well so have decided to take a break. A little time reading here and playing a couple of games of Words with Friends and I'll tackle it again.
Bearisgray, a previous poster had me check the bobbin case and there doesn't seem to be a problem there. The leaf spring is not bent and there are no burrs or rough spots. And at $40-$50 for a new one, I really don't want to put good money after bad on this machine.
You know, it's funny, but I have a habit of naming inanimate objects. The Singer 128 was Goody the moment I picked her up from Goodwill (not very inventive, I know). The 15-88 is Estelle for the aunt from whom I inherited her. Even had a car one time that had a bad habit of getting the horn stuck when the keychain clicker didn't work properly. Named him Horatio after Forester's Horatio Hornblower. But I've had this machine for three weeks now and it doesn't have a name. Guess that should tell me something. LOLOLOL