Brakes
Unfortunatly the wheel nuts are all quite solidly siezed, and the badly bent wheel nut spanner that came with the Yellow Truck provided no leverage at all. Might still be able to get them off as I may have a better wheel brace in my tool box, otherwise it'll have to be a job for our local mechanic.
Being a bit clever, we looked through the inspection ports on the inside of the wheel hubs. Depressing the brake pedal causes no movement on the front shoes, which seem to be siezed 'out', while there's some slight movement in the rear shoes.
So, they'll need to be inspected...
It might be easier to figure out the electrics first...