crosley washer spinning erraticly

I hope someone has some help for this problem. My front loading washer stops part way thru the cycle and you can hear a humming from the motor. With the front cover off I can reach in to the drive belt, push it to get it to go, and the tub will sluggishly start going back and forth, then go around slowly, and eventually stop again. Then I can repeat the process. It acts like the motor is tired and about worn out.