I'm working on a Jacobsen HR5111, with 500 hours on it. The problem I'm trying to fix is a "stiff" traction pedal. everything works, it goes forward and reverse as it should. but the amount of pressure it takes to move the pedal is definitely more than normal. with the engine off, it feels fine. start it up, and it's stiff. all linkage is as it should be, the traction damper is fine, and the centering springs are adjusted right. I've replaced both hydro filters, and inspected all of the valves in the 4wd valve block. any ideas?