
His guess,,,, your Old "OPTO" equipment is very probably not compatible to his, upgraded to current requirements, equipment!
Further,,, If you install a ground to the controller/battery and connects it to the radio ground his limiter should work.
I would bet a "Dollar to a Donut"


Thus,,,, as at the Worlds, after you prove your equipment is not compatible with ours,,,,, we will test your "Stuff", and if it is proved to be within specified limits you will be allowed to use your equipment!
Lastly,,, Steve recommended the Castle Edge 75 Lite controller !


Scotty