I have a Cal Spa that is at least 10 years old. It has two motors/pumps. Pump #1 has a low speed that is used for filtering and heating and a high speed when you want to feel the jets. Pump #2 is just the high speed. Pump #1 will not come on when the system calls for heat or filter cycle, it just hums. It doesn't pop the breaker, after humming for a few seconds I can hear a relay in the tub click off.
However if I push the jets button several time it will sometimes come on. Or if I turn on pump #2 after a couple of minutes #1 will come on. Once pump #1 has been spinning I can stop it briefly and then start it up again and it will start on slow speed.
I've been reading on this site about replacing the start-up capacitor, does my problem sound like that would be the cause? I had this same problem with pump #1 a year or two ago, but then it started working again.