Model 1810 transmission valves leaking

[Bmech]

I have a model 1810, and the two transmission valves on the top front of the transmission began leaking after I pushed the tractor on a trailer. My question is, are the valves repairable or should they be replaced? I completely dissassembled the trans, and found no damage internally. It drives good, but leaks fluid while running. When the engine is shut down I can hear a burp coming from the transmission valves. New valves are about $150 each, and Iam not sure I want to spend that kind of money on the tractor.