small motor problem on singer type machine?

I have a novum sewing machine (Mark III) - the type with a motor to balance wheel, rubber belt drive. Just like a Singer. The little motor at the back is a sew-tric make. It has a small capacitor in it that I assume is the start/run cap. The motor went 'puff' and tripped house fuse. There was some smoke from motor. I'm fairly sure it was from the capacitor inside. Where can I buy such caps (three leads one side, two the other) and how to repair motor. Any manual available? Any one seen this problem before and fixed it? Thanks for your time. Neil