Motor start capacitor for Emerson 1-1/8 hp
If the motor won't get up to speed, it is most likely bad bearings either in the headstock or in the motor. It can also be dust in the centrifugal switch inside the motor. But, capacitors can and do go bad, sometimes the liquid leaks out or dries up, or contacts break off of them.
Be sure to order the correct size capacitor. Specify the size in a note on your order, or tell me which motor it is for.