I would do a thorough clean up - is there any dried up oil keeping the machine from running properly. Is the foot control ok. Do the wires to it work right. DH does an electrical test on the wires. You can get a lot from sew-classic. She does have brushes - not too hard to change. There is only one screw holding the motor in the 403 - it is in the middle of the black square thingy next to the motor. Unscrew that screw - then un-hook the electric fasteners - you might want to mark them so you can return them to the right place. Then the motor might or might not drop out. I've had to take off the hand wheel and tap on a block of wood very lightly to get it to start - some times the motor goes shooting out so be careful. Maybe you can find a motor rebuild shop if needed then put the motor back just like you got it out.