This is the new toy I'm getting tomorrow. The grinder I have now still works BUT the bit is frozen to the shaft. I've tried everything from WD40 to a hammer and still can't remove it. Its old anyway. This happened when we were going out vending and I was busy making pieces and not paying much attention to losening the grinding head when I wasn't using it.
I'll hang on to it just in case I start teaching a class or some strong man comes along and losens the head for me. Wish me luck.