To know if the cap is on value, you need a capacitor testing meter, or such a scale on your volt meter. To see if the cap is functioning properly under working conditions, a capacitor ESR meter is required. The only other reliable way to test them, is to change them.
It is also possible that the motor is defective. I have seen defective motors in appliances from time to time.
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Jerry G. ======
15 seconds. (On the 200k ohm scale, the resistance slowly rises until it shows "open".) Does this mean that they are bad? Is there any other thing I can test without a capacitor meter?