I have got a Raleigh Evo folding ebike and after riding for approx 3 years or so the motor seamed to disengage and make a strange noise. I was about to give up when i read on another post which i tried. Lay your bike down and dribble light oil into the motor hub and let it soak in. Give it a spin and in my case it freed up the sticking parts. Hope this helps others.
