Is there noise coming from the motor or from the gear box behind the bobbin? On my 223 the gear box is open to the bobbin side so I would open that up and clean out the gear box. It could stress the motor if it full of lint and dried up oil. Then I would put as much grease back in as you take out. Vaseline should do the job nicely.
You can buy a whole new tension on line if you need to. A tension from an old derelict might be made to fit as well. It won't match but the machine should work ok. You can also figure that a Singer 66 only has a couple parts so put it together like that and see how she sews. You don't have numbers on a 66 so you do have to go by how it feels to adjust the tension.
Those are nice machines. I like the ss, zz, and blind hem abilities. I'm thinking it would be nice on a treadle if the motor goes out.
Last edited by miriam; 09-21-2016 at 02:49 AM.