There are two signals to the controller that go down separate wires. One has a pulsing signal for how fast you're pedalling, which is given by the light going through the castellations. The other is a 5v analogue signal given by measuring the length of the pulses, which decrease as you pedal harder. The actual operation is pretty well fool-proof regarding the electronics and the way it gets those signals, so any intermittence in the power is more likely to be a connection problem. If the chain comes off, it normally damages or pulls the wires into the tplastic part, so have a good look at those, or you can test them with a meter if it packs up completely.ripped it all apart again and found a slight uneven backplate where its been crunched - cleaned up and oiled it instead - seems better at least - agree though, its a shocking design for the price!
Finally back together - and looks like it works - in other words its not giving errors and reads the speed etc ok. when i pedal and turn on assist is spins up the back wheel in pulses - no idea if that's because its in the air and the torque sensor isn't detecting changes in torque or something - never ridden it so don't know how it behaves.
Lets hope the nephew looks after it this time...considering it's his way to work you'd hope so!!
Thanks for all the help on here - really got me through this mess!
I'm now looking for a better specced "project" e-bike for myself - with a crank housed motor....can't be doing with all these bare wires and custom brake discs etc lolI've got a full suspension pedal only Cube MTB which i built myself and love, but after years of saying i'd never get an e-bike, dodgy knee ligaments are now forcing me to reconsider.... Expect me around again soon
One other thing that I forgot to mention is that you can remove a couple of springs to get maximum power with less pedal effort.