99 e300 here is what is happening:
sometimes (50% of the time I am driving the car I hear a clicking noise coming from behind the dash near the ignition switch. If I lift the key the or move it some the clicking will stop. When the clicking sound is taking place I can feel the key move. The clicking sound is not as loud as the sound that takes place when you first insert the ignition key but still pretty pronounced. Also I have noticed the horn or sunroof does not work unless I lift the key slightly when driving.

I am down to 1 key. The other key stopped working (stop being recognized by the ignition switch) about a year ago.

This is probably a solution for the dealer to fix but my fear is potentially waisting $300.00 because I am sure that is the first suggestion will be that I need a new key. If that fixes the problem great but if it doesn't, I am sure a super-expensive new ignition switch will require an entirely different set of keys as well (another $300 for each key)

Any suggestions on how to proceed?