Originally Posted by
John K Jordan
A "short" would be two things touching which might show a reduced resistance with a sensitive meter, not necessarily zero. An "open" or break would have infinite resistance along that path. However, the small motors I've worked on had windings connected in what might seem like complicated ways. I'm certainly NOT a motor expert and have never worked on that type of motor. If you want I can ask my friend Joe who knows everything about motors.
I've had several run and start motor capacitors fail on various machines. In my case, each failure was obvious by a breach somewhere on the housing through which some internal substance had escaped, and a strongly pungent smell. I have a capacitor tester but if not I would try touching the leads of an ohm meter (set to a high resistance range) to each of the leads of the disconnected capacitor and noting the needle movement as the capacitor charged and discharged. I haven't tried this with an AC capacitor used on motors but have on polarized elecrolytic DC capacitors. It's easier an analog meter - the needle will start low (zero) and move to a higher resistance as the capacitor charges.
Any motor shop or electrical supply house should have a capacitor for that motor and they are relatively inexpensive. If in doubt I'd might buy one and if it didn't fix it keep it for a spare. One shop I visited had hundreds of different sizes in stock. Unfortunately the didn't have the one I needed for the Jet mini lathe I wanted to put back into use for a class. I had to pull one from another lathe and order one from Jet at exorbitant cost compared to Rikon and other equipment suppliers. (editorial comment) Note that a similar but not exact capacitor will work as long as it is rated for at least the voltage and capacitance - it doesn't have to be the same size unless you want it to fit in the can the old one came out of.
Another option is simpler but also a lot more work - disconnect the motor and carry it to a motor shop where they can quickly test and repair if needed, likely far less than buying a new motor.
I don't remember, does the motor have a thermal overload reset button?
JKJ