I've been having trouble with the electric bike; about 90% of the time it does nothing, 9% of the time it runs at half speed, and 1% at full speed. Not good.
I took the throttle apart, there's really not much to it, and I don't think that's gone wrong.
I got a circuit diagram from the internet, and took the controller apart. No user servicable parts inside. So I contacted alienocean because it was them that sold the kit (and still do) and explained the problem, expecting to have to fork out £32 for a new controller. From Jim, I got some advice - he suggested "remove the casing from the side of the motor and check for water ingress before coughing up for a new controller". So I did that, it wasn't difficult. I couldn't see any water inside, but a few drips of oil came out. So I left it for some hours in a dry room, in case there was a bit of moisture inside, then added a few glugs of hydraulic fluid to top up the oil, and reassembled.
Full speed ahead.
I'll leave it a bit and test it now and then, but I think this is a good demonstration of why you should buy things from people who give you good customer service. Alienocean have been selling electric bikes for several years, and know what they're doing, and it's always a good idea to buy from people who know their stuff.