Quick update... (on 1998 E320 "seat click")
I wrote a letter to MB Canada complaining about this. Got a reply from their PR
flack stating that the car was out of warranty and that I had not brought the matter up in time (all true, I even said this in my letter) but, and here's the slightly better news, I should take it in for "evaluation and etimate" at the dealer's place (don't like the "estimate" bit) and see if the dealer could "do anything for me". Message seemed to be "MB corporate won't lift a finger - except the middle one, perhaps - but the dealer wants to sell you your next car..."
So, I took it in for test drive. Tom, the dealer's Service Consultant, was very polite and concerned. Rick, the 250 pound test driver, was also very solicitous and helpful - but he could NOT make the seat click! We swapped the driving and I (165 pounds) could not make it click either. What a p****r! Now, it was snowy, so we had a bit of trouble getting real "g" forces on the car (and seat.) Finally, in a ploughed but wet shopping mall carpark we did some gyrations, to about +/- 1/4 "g" - still no seat clicks!
Rick said his weight might have reset some loose rail or bushing. Finally, Tom said to wait for it to reoccur and bring it in right away. Neither of them had any doubt that I had experienced the "seat click" right up to bringing the car in.
On the way to work that morning, guess what.. seat still NOT clicking, yet. Nor on way home. But I'm sure it has not fixed itself.