Hi everyone, I wonder if you can help me with my troubles

My 2nd 38 machine has had transport issues since I bought it. I figured it was down to the capstan belt (which seemed likely at the time) however having taken the machine apart to change the belt, the existing one is in really good condition..

I'm thinking this means probably bad news as the capstan can turn manually however it won't turn by the machines power so I was guessing it could be the capstan motor? Does this have its own fuse that could have blown? As the rest of the machine works fine.

Thanks for any help you can give me