I have a Super Z that I just got and is my first zero turn mower. I was mowing and the right shift lever start going forward real easy and the mower acted like it wasn't going. It does it and then it seems like it goes ok for a little bit then does it again. I checked the belt and it looks ok. The lever moving real easy is what has me concerned that the pump may be bad. Can you rebuild the pump? Thanks for any help.