350C loses reverse drive after operating properly

[dozingdozer]

Hi folks,

My 75 350c, with a slight leak on the reverser coolent return line, works fine and pushes well but than after 20 or 30 minutes reverse direction gets weaker until it doesn't engage. As it starts to go i can get it to operate in reverse by pushing in and letting out clutch pedal. No loss in forward. I haven't changes the fluid filters yet, waiting for 5ft of snow to melt , but the fluid is relativly new in reverser and up to level. when problem happens i let it sit and cool down for an hour and i can then get 5-10 minutes of reverse power out of it and then it fails again. any thoughts or suggestions?

thanks,

DD