I was rather pleased with myself for fixing the loose rear wash hose above the passenger wheel arch, but now find that the rear wiper blade gets stuck half cycle as the glass dries out. Presumably this is all part of the dodgy motor syndrome, which has flared up after all my fiddling with the nozzle. I can get it going with a push-start but I suppose it will eventually burn the motor out. I was wondering if slightly loosening the mounting bolt would help ease the drag of the blade over the glass and so help it glide more easily. Is this possible? Any thoughts?

Er, i think this will involve more than loosening the bolt. The motor and drive mechanism is quite strong, if it isn't working I think you may have to delve deeper. It could be a dirty contact plate within the wormwheel housing, stopping the leccy at the same point everytime, or you could have stripped teeth on the wormwheel. Either way I think you'll have to strip it to find out.