too hot only affecting mid range?

[Serum]

I would try another transmitter/receiver combo. If that doesn't help, the speedo needs to be returned for a check.

[auto2]

Ok I'l try .

[BrianG]

Or, if you don't have another Tx/Rx, use the steering port for the throttle as a test. You know the steering has full range. And then to make sure, put the steering cable in the throttle port and see if steering has full and linear travel.