I've got a 200C LC excavator serial FF200CX504087 that I inherited in a buyout and it continues to give me fits. It's one of those machines that prove kids don't get spanked enough anymore! All of that to say, over the last 8 months the drive has become weaker and weaker. It lives at remote sites often so access to it is difficult and the operators do operator stuff to keep going and so often it's dumb crap you have to undo before you get to troubleshooting the real problem. Needless to say it's not an ideal situation by any means. This fine day though, the guys called and said it won't drive on the right side with the pedal but when the right joystick is pulled back it starts driving. I should say one of the things that have been done to this was replacing the rotator manifold. I didn't try to rebuild it because the reman from Deere was only a few hundred dollars more than the seal kit. I don't believe the boom functions go through the rotator so I don't think there's crossover there. Also the joysticks are pilot controls not electric so I can't see a short there. Kinda scratching my head! Any thoughts would be appreciated.
Moving the other control makes the pump go to more stroke, providing more flow. It is enough to get the track motor moving. It is a common thing, I can get my 120 to spin a track at high speed while it is off the ground by doing that. I cannot diagnose your issue but I at least wanted to tell you that connection.
Check whether the oil return pipe of the center joint is leaking or not.
The 4 spool side of the main control valve has Right track ,Bucket , Boom1 and Arm2 and are supplied by Pump1. Check the Pump1 control pressure when using the right track only and again when using the right track and boom function. To get into a Deere C series or Hitachi ZX -1 excavator service mode. Press and hold the set button then key on or start. After bulb check release the button. Then use the select button to scroll. Item #4 is the Pump1 control pressure.