Yea, that particular foot control is pretty bad.
Sometimes we can bend a prong to make the connection to the motor better. But the white plastic on those old Pfaffs is quite brittle and breaks easily, so you have to be careful not to put any stress on that part.
Sometimes it's just a break inside the cord. In that case, we cut a couple inches off the end of the cord and re-wire it. You'll know where a break is by pressing the foot control and wiggling the cord. If you wiggle one end and it cuts out, you know that's where it is. You've got 4 spots that it could be.
I really doubt that it would be a motor problem. That's a well-made motor. Of course, if the previous owner sewed a whole lot, it's possible that the motor brushes could be worn out. But that's a pretty easy fix. It couldn't hurt to clean the armature if you're going inside the motor. That might help it move a bit quicker.