Replacement capacitor for a motor
My band saw has a 5 hp motor that runs on 220V. It recently had trouble starting up and I determined that the capacitor that is mounted externally on it was bad (it was cracked and had a hard, foam-like material that was protruding from the crack). The plate on the motor calls for a 40 microfarad capacitor, but I'm having trouble finding one with precisely that spec. I can find ones that are rated at 45-50 microfarads and 33-37 microfarads, but not one whose range covers 40. I've been given conflicting advice: 1) it's ok to go with a slightly higher capacitance, but going lower than the spec could cause problems, and 2) it's ok to go with a slightly lower capacitance, but one that's above spec will possibly damage the motor. Which is it?
While I continue to search for the right capacitor, I'd like to hear from folks who can clarify the issues and potential problems when using a capacitor whose spec doesn't quite match the name plate rating.