Take a good sized screw driver with plastic head or something on that order. Tap on the head of the motor where the brushes are. Really need someone to click switch off and on while doing this. Not that you can't do it by yourself. I have found a lot of times the brushes are sticking. Don't beat it hard or on the sides. On some motors you can knock the magenets loose. If you have a meter you can find connections to motor and make sure your getting power out of your solenoids.
Proud Member of Team Geezer
Charlie Weaver USN/ENC 1965-1979