Most are 90 volt DC motors. Difficult to test! Usually there are two wires for power (+ & -) and two wires to a tachometer pickup so the computer knows how fast the motor is really turning.
So perhaps (carefully) check the voltage at the power wires and see how many volts are there? It won't be 90 volts usually (because 90 would be going very fast) but what it should do is ramp up from zero to perhaps 20 or 25 volts for a smooth startup. Use the higher voltage scales on your DVOM when starting your test. Don't let low voltages frighten you into thinking the voltage is too low--the computer won't send more power to the motor until it knows what speed it (the motor) is turning. Safety is the issue here.
Careful: I said most above, some are not DC motors! Some are variable frequency AC motors.
