Under normal conditions in today's industry, a pool motor should last 5-10 years. If protected and properly maintained the later should be reached fairly easily. From time to time, problems do arise. We all know how expensive it is to call a service company and pay labor charges, so here is a few insider tips of the pro's to determine some issues. Once you have determined where the problem lies, you can move forward with the proper fix.
Symptom; Motor will not start, it hums, buzzes or smokes.
a. Check the shaft, does it turn freely? If not, check impeller and diffuser for debris or breakage
b. check bearings
c. test the capacitor & replace as needed
d. Check the starting switch for proper adjustment
e. could it have a short in windings....if so replacement is answer
Symptom; Motor Loud
a. Bad bearings due to leaking seal (leaking seals are usually caused by other problems that will need addressing)
b. worn bearings or end bells (9 out of 10 times it will be in your best interest to replace)
c. improper voltage to motor (call electrician)
Symptom; Motor runs HOT and shuts off
a. pump not sized properly
b. wrong impellar
c. clogged vents or restricted suction due to dirty baskets
Symptom; Motor smokes
a. windings shorted
b. improper voltage
c.welded starting switch
d. capacitor failure
Replacing the motor does not always fix the problem. Knowing what caused the problem, and fixing that issue will prevent premature failure of new motor's. If your motor is over 5 years old, and you have determined that it needs rebuilding, it may be in your best interest to go ahead and replace it. Good luck...& happy shooting!