Thanks for the response. I have tried a couple of different controllers and sub-controllers that came in the parts boxes with the bike and they do the same thing as well unfortunately, although I have no idea if they worked in the first place.

I was hoping that someone else had seen the servo pulley behave in the same way and had a definitive solution. It seems that when the controllers give up, everything stops working rather than it behaving oddly? Maybe the TPS could be the cause or something else that feeds an input into the control units?

Cheers