The guy a was watching really used a air chisel, with a special attachment made for driving a valve guide. It probably works pretty well, if you know what you are doing. This guy got fired a few weeks later, for doing something else, I think he forgot to roll the window up on a car he parked outside. That night, the rats got in the car through the open window, and ate half of the foam and leather on the drivers seat.

That's really good advice on the valve stems and shims. Thanks for sharing with us, for all the times I have had a shim out, I never thought about a wear pattern.