Throttle problem
At the risk of not knowing what I'm doing here, I didn't quite get the statement of the problem: does the throttle channel not work or is it the throttle high warning feature that doesn't work and therefore disables the TX?
Here's where I get into trouble, I don't have an RD-6000 but I do have practically every other Airtonics radio, and on the Stylus, the throttle warning on turn on can be disabled in the menus. I'd suggest you check on the RD or manual and see if you can do that. I thought the feature nice at first and a major annoyance after awhile.