Perhaps those posting can send you a new one. From my experience, a late model 300 that is going to be in better condition than what you currently have might cost over $50.
To fix the one you have I'd measure the amperage draw when working and when 'bogged down' If the amperage goes up then take it apart and look for a source of binding. If the amperage goes down when running slow, look for a poor electrical connection or bad wiring.