mower electric motor?

Hi have three mower electric motors 1kW. from 3 off mowers. First mower failure to start changed the Capacitor outcome fixed. Next mower motor older so stripped down motor stripped checked windings , brgs. ect all good.
Last motor some rust to motor casing, stripped resistance on windings good, no earth problems, winding insulation test good, brgs. good. However when reasembled and connected rotor which is free to rotate when not switch on. Then switched on " heavy buzzing " as if a capacitor so changed for a replacement Cap. of same rating. Still no rotation, double checked connection and changed over Strart & Run connections but still no rotation. Rotor " L ocks up " motor shaft end float ect. good. Any ideas folkes.
regards,
mike.