I searched the forum and can't find the exact problem I'm having. I have a scag tiger cub 48 " deck Recently, when sitting in the machine, the left handle and wheel became very weak and not keeping up pace with the right handles wheel. The past two days once you run the machine for about 15 mins you basically loose all power in the left handle on any kind of decline or incline. What I have done so far: rebuilt hydro pump (all seals). When I opened the pump there was no metal shavings or other wear. The valve attached to the handle seemed to move freely without problem. Changed belt. Changed tension spring. Purged the system and I made sure 5/8 hex nuts r tight again. There is a hydro leak near the filter. Is there any chance this is drawing in air? Please any help on what it could be, im praying it's not a wheel pump (which I don't think it is because when I purged it, it moved freely without any noise for 10 mins) or hydro pump cause there both big money.