KO esprit II help

[Rick-J]

I have an esprit II that I have converted to 2.4ghz. Its been great but the throttle stick seems to be faulty. It does not work when brakes are applied. I know it is the stick as I reversed the speedo and servo so that the throttle controlled the servo. And when pulling the stick back the servo jitters and does not always turn but forwards is fine. Does anybody know if it can be fixed? Can you get the parts? Don't really want to replace it with something like a core 2.4ghz handset unless I have to. Thanks