I'd like one of those testing and cleaning machines, we had one in high school shop class, quite handy.
Recently I've been cleanings some in an ultrasonic cleaner with simple green and water. I made up a nice little rack they drop in with the electrodes pointing up and a handle on it to place and retrieve it from the cleaner. It works great on sooty/fouled plugs, not sure about well used caked on hard carbon, haven't tried any like that.
Grigg
