Thanks for the quick reply
The belt always fails due to significant teeth reduction along roughly 3" of its length (never snapped a belt yet! [fingers crossed]).
Removed the pinion gear to test transmission:- Feels smooth with no binding. Resistance of the drive feels a lot like a gear diff with 10K oil in it. i.e. if you spin the rear wheels then they come to a stop within approx 1 free wheel rotation. Also when you spin the rear axle by one wheel the diff does not activate.
The belt easily rotates 90 degrees. I like your tip to gauge the belt by the way, I have only seen / been told to measure deflection which to me seems daft if as you don't have a set force applied.
I so wish someone sold a belt tension like they do for timing belts on cars.
I currently run a Vampire SR+ Speedo. I have never heard of different software for it and the manual does not mention that there is Mod/Stock options. I will look into that. Is it possible the speedo could be somehow giving the motor to much current? [The motor has not been tampered with or adjusted in anyway, its straight out the box]
Thanks again for your thoughts on this.
p.s. would the slipper being too tight overload the motor? [really grabbing at straws now]