Hi The fan has an electrical leak, possible loss of insulation in the winding that has nothing to do with the capacitor and you will not be able to discover it with a low voltage instrument and less direct current like a tester. To check the leak, lower the engine and apply voltage with an exclusive power cut between the ground and the terminal block (each cable). Another way is with a series lamp with a filament bulb of 5w or less, in this case, if you turn on or jump the power cutter of the house, there is a declared leak. In the best case, you can reverse the line in the terminal of the fan and it may work another season (you remove the leakage from the discharge point and reduce it to less than 30 mA). The leak can be the same for the neutral, although in this case it does not happen (temporarily). In conclusion, most likely you should replace that engine as it is the most common. Greetings to all.