Nice tear down. Those are awesome tools made to last and to be serviceable forever. You got a nice little grinder there that has top of the line power and gears made to handle it. I'm sure he made his pay many times over what he paid for that tool so it served him well. I would snatch that sucker in a heartbeat if I came across one at a garage sale or anywhere. Yeap it's time for you to adjust some valves or to do some motorcycle related task.