Pool pump buzzes...

[mwinter]

The motor was working fine but I was having a low pressure problem so I replaced the bushing behind the impeller. Now that I've put it back together the motor just buzzes but won't start. I suspect that perhaps my original low pressure problem is due to the motor wearing out and now that I've replaced the bushing the fitting is more snug and the motor simply won't start because of that. Are there other possibilities? My pool is only about 4 years old. The motor is a 2 HP Centurion with a WhisperFlo pump.