I think I've found the problem with the Z's windhield wiper motor... Working with my electric r/c race boats, I found out that one was 'slow' because the MAGNETS in the motor had gone bad because of the heat involved over time. Over time (25+years), and with the motor under a steel panel, catching rays/heat (mine is a Florida car), the old-style magnets in the windshield wiper motors, should have gone bad, or weak, which means that you can put direct power from the battery, and you're still not going to get the right speed or strength. So the problem then would be to find out if you can replace the magnets, which are probably glued in. These could be chipped out or maybe put in an oven to (burn?) off the glue. Then you'd need to get or make new magnets. I suppose you could get the materials to cast magnets (like ceramics) but then you still need to zap them to activate the part. That might need special equipment. Maybe there is somebody in this club that has contacts or experience with magnet manufacture. Thx