Last friday my 600hour 04 Lazer Z had some hydro issues. The left hydro (when sitting on it) went out while on a job. The actual seal right behind the pulley went out but lead to deeper issues. When I got it home and taken apart I realized how damaged the internals (especially the pistons) were. While in there I pulled the other pump for inspection since there was metal in the system from the 1st pump going out. The other pump, while not in bad condition had metal in it so I decided to order 2 new pumps. The OEM hydro gear units are out of stock and aparently on backorder for 2 weeks. The generic pumps the dealer I worked with carries are made by the Parker company (the company who makes OEM wheel motors for the exmarks). The 2 pumps came yesterday and I swapped all the parts over and got them on the maching. I pulled all of the lines, resivoir and filter assembly, flushed them with new oil, compressed air and thoroughly cleaned the tank out. Ran about 5-6 quarts of fresh oil through the wheel motors, sucked in one port forced out the other to clean them all out. Got it all together, primed the system before starting it to make sure some oil was in there ...staying up til 2am to get my cutting back on track, which class at 9am! Well one side worked and the other was not driving the wheel motor at all. After a lot of time it was aparent one of the new hydros was not working. When the pressurized line going from the hydro to the wheel motor was taken off NOTHING came out, while the other side squirted out like crazy (as expected). Some time later I figured it would be smart to work on the better of the 2 origional pumps...I cleaned out the good condition, working origional hydro (the one that did not fail just had a bit of metal particulate in it). Got it all back on the mower, primed some oil through it once again...still the wheel motor wont turn on its own. However this time around the pressurized lines going from the pump to the wheel motor DOES in fact have pressurized oil going through them. I know there's air in the system but its not even moving the slightest amount. The distributor is sending out a new pump for the defective one but that does not affect the wheel motor not responding to the pump. This was not even the side that gave out on me initially. I have all the lines and ports just as they were origionally. I cant figure out whats going on and it been sitting almost a week killing me. I just dont understand how this very well maintained 600hr machine is causing me this many issues. Any help would be great and very much appreciated.