Bobbin winder Singer 185k
 

DH just replaced the belt. Original belt was a flat one but store was out of them so he brought home a round belt and machine seems to work ok after installation. Man at store said bring it back if it doesn’t work out. Problem is: Bobbin winder has become sluggish and touchy so I have to baby it along. I suppose I should replace the bobbin tire or could there be another reason ?

The bobbin tire could need replacing but I would not use a round rubber belt. They're always too tight and put strain on the motor. Get a proper belt and see if that makes a difference. Remember, the belt needs to be fairly loose, just tight enough so it doesn't slip.

Cari