As other have already stated, the reason the motor fails is due to water ingress. Drilling a small hole at the bottom can help drain the water that is trapped inside. The noise from the motor is likely from dirt and corrosion and lack of lubrication. I needs to be removes, cleaned and lubricated. After that, it might still be no good. This is risk of second hand motors. Lots of posts with photos on this topic. Its a pretty common problem for cars that are parked outside regularly. 

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