I have switched the valve from remote to 3 point operation before. Then forgot to move the control lever from constant pumping to the normal 3 point operation position. The first time I did it I was getting a loud chatter noise from the clutch area and I thought something was going on it. Now I know what to do if I hear it.
Just a thought. Its hard to believe you would have clutch problems with only 500 hours. I have over 2000 hours on mine and never have touched the clutch.