Banged on the motor with the switch in the low position, and it started moving

kept banging till it moved well. Noticed a rebuild sticker on the unit. Time to buy a new one, or should I get one from the boneyard?? I saw about 10 intact ones this weekend. My guess is get the rebuilt one since this may be a common problem
------------------
Frank W
90 5.0 LX coupe Daily driver. Silencer removed, K&N filter. Flexalite fan, 3 core radiator. FMS flywheel and Clutch Finally rebuilt T-5.
74 Chevy Laguna Type S-3 305 apart in garage, getting a 454 to put next to it
www.chevellepages.com/folingo