I just got my X475 and am still trying to learn about it. I notice my deck will sometime raise/lower and sometimes will not do anything. I haven't mess with it much but I want to test it to see if it has to be at full throttle. I notice it will not raise/lower when I have the throttle at idle. Also, make sure you have the correct amount of oil in the transaxle. I don't know enough to know how the system works with pumps and pressure. It could be a pump problem or just a valve problem if you have enough oil in the system.
Turn's out the height control knob was screwed up. when I set the height to a
high setting, the lift arm's came up to the frame, an easy fix, the mower deck
need's to be reset, over all I am really happy with the tractor.