If he disassembles ... he has few components, imagine that he walks slowly if he was holding the rotor with his hand and some of the smell of long talk ... if you can give me a solution I would appreciate it ... I thought there were internal Roses but no...
Disassemble the base of the sander and check if the rotor turns smooth, if it turns smooth, turn it on and see if it turns the engine or just tries to turn and emits a hum, if so try to turn the rotor with your hand, if it is hard The fault is due to wear of bushings or bearings, luck and comments.