Hydro problem

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Last wednesday a small branch with my mower and I broke a small Oring on the hydraulic pump. I took off the hydraulic pump and I went to the dealer and they changed me the shaft seal on one side and the hydraulic pump on the other. Yesterday I took on the hydraulic, and I tried the mower. I can go forward, left and right but I can barely go backward... Is someboy know why?

I need this mower to run so bad...

Thanks!

[MowerMedic77]

http://www.lawnsite.com/showthread.php?t=144040

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The ztr is a cub cadet tank m72 with a kawasaki 29 hp liquid cooled. The hydro pumps are hydro gear.
Year 2006
Thanks