Help! Pool motor starts intemittently
 

Hope someone can help me with a real head-scratcher. I've had a
swimming pool with a 1/12 horsepower motor for 15+ years. I've replaced
motor a few times without incident. Earlier this year, I turned it off
to clean and it wouldn't turn back on. Replaced motor twice; same
problem. Some times it starts, some time it doesn't. Even when it
doesn't start, basic electric meter shows current reaching the motor.
I'm stumped. Any ideas?