I've been working on my '51 TO20. Started with just fixing the brakes but found that my transmission/hydraulic oil was contaminated with water and decided to do something about that. I drained it, took off all the covers, removed the PTO shaft, the pump, the upper lift section, and the differential. I partially disassembled the pump and then I cleaned and cleaned and cleaned everything. I did the brakes while putting everything back together and those are not a problem. But, the lift arms have raised to full up position and will not go back down. Even after the tractor has been shut off for over an hour, I still cannot push them down. My wife suggested I just let it run for awhile and see if it will fix itself. I may do that just to keep her happy--always good to have a happy wife. But I'm hoping for some better suggestions here.