Turntable Motor does/ does not spin

I've got a turntable that sometimes will turn and sometimes will not. Pulling off the platter, turning it upside down, etc., you can easily find the little motor. Belt-drive type.

This motor has a spindle that sometimes will spin and sometimes will not. When it doesn't go on of its own accord, a gentle twist and the spindle will take off and run smoothly.

How do I convince it that it would be happiest spinning away all the time?