1985 300D: the ignition switch tumbler has failed. Thankfully I was able to turn the key to position 1 and shut off the engine using the STOP lever on the engine. I then removed the ground on the battery.

With the key in position 1, I am able to insert a release wire through the hole in the tumbler about 1 inch. With the wire inserted I am still unable to unscrew the screw on cap. It is loose (moves from side to side) but the cap will not turn counterclockwise.

I have done this procedure a few times in the past and never had this problem. I am guessing that the square pin in the tumbler is not retracting into the tumbler far enough to allow the screw on cap to turn.

The tumbler is a genuine MBZ part that is only 2 years old.

Any suggestions? Thanks very much.