I have a Grasshopper ZTR that has started giving me problems with one of the pumps. The other day while on a job, whenever the right lever was pushes of pulled, the tire wouldnt move and I heard only a clicking type noise. I tried changing the fluid and filter. It then would run fine for about 5 or 10 minutes and then the problem re-occurred. I found the schmatic of the pump online and have been looking at it but am unsure of which part within it may be causing the problem. Any suggestions would be great.