weirdness trying to use a DX6i

[VintageRacer]

This morning I switched the spring from the left stick to the right on my DX6i air transmitter so my son could use it for his car. I don't fly heli's anymore and his hands have grown since I bought him his etronix stick transmitter which is quite small.

The spring switch went well but we couldn't get the throttle chanel to work with the esc. The esc works on all of the other chanels (currently on the the rudder chanel) which indicates a problem with the throttle chanel, however, the monitor function shows it to be working as expected and the steering servo works normally when connected to the throttle chanel.

Anyone got any thoughts on something I might have missed.