I have a Hustler Fastrack with a drive motor problem. The hydrogear unit on the right side does not drive. It is a 311-2600R / 788059. Is it a good idea to take this unit apart and find the failed pieces and rebuild? or Is it best to just buy a new unit at about $850? My mower is just over 3 years old, so warranty is probably not an option. Any advice will be appreciated!