Thought about this all day, then it struck me. In the process of changing the ignition switch I accidently pulled the steering lock cylinder out-dropped it before I looked at it. It took a shile to figure out how to put it back in, correctly I thought. I think I must have it off by 180 degrees and the key buzzer switch is in constant contact with the flat side of the bottom of the ignition, causing constant on condition. Steering lock cylinder needs to be flipped 180 degrees.
Good news--found the problem. Bad news--now have to remove steering lock assembly to rectify. Oh well, it took me nine hours over 3 evenings to change switch, but only one hour to put it back together. Should be able to correct in 2 or 3 hours max, if not shorter. It won't be nearly as hard (or intimidating) now that I've done it. Experience is a great teacher.
'02 C230 Kompressor
'89 560 SEL "Frau BlueCar" (retired April 2004)