Hi, nickwe21!
The only symptom I had is the car wouldn't start. The only decent mechanic is laid up for 6 or 8 weeks, and I couldn't work on it .. so it went to the Mercedes dealer. Normally it would be packed away for the winter, but I needed a car. To answer your other question: No, I've never seen a leak under it. Which is why the "explanation" I was getting didn't sound right... but they were supposed to be the experts, so I tried to find another TCM and consulted the forum here.
But your suggestion of checking under the carpet is great! I can do that as soon as the weather abates, or if it does it again! Thanks a lot!