I had dead batteries in the motor thermometer. It's actually an aquarium thermometer, with the sensor blu-tacked to the torque arm. This means that if the motor starts to get hotter than I'd like, at least I know that I have a problem and I can let it cool down for a while.
I also checked the rear brake (still plenty of wear), remover the rear reflector (I don't think it's actually useful, because I carry a small rear light as part of my emergency kit).
I've changed the pannier bag; the one I was using before, has clips that are difficult to get onto the rack, yet I've found a couple of times that they're able to bounce out. So I'm trying out a different pannier.
The throttle cable was showing signs of wear; I thnk I might have nipped it in something. It still works, so I've wrapped the slightly damaged part in duct tape, so that should stop it getting worse.
I also made up a new cable for connecting three 14.8 volt batteries in series; that gives me 50 volts when the batteries are fresh. The old cable was beginning to look a bit grotty. The motor is rated for 36 volts, so over-volting it like this gives me a bit more oomph, and even when the batteries are down to 42 volts, I'm still getting a good push.