Thanks gentlemen,
I think before I resort to door panel removal I am going to try some cleaning and lubing with a dry silicone spray in the side tracks. That is a tip I got from an auto glass guy yesterday.
Achim, the W166 paired with the 4 cyl diesel bluetec engine is sublime combo. No run flat tires. I get 30 mph downhill . The handling, speed and response rivals my 250 SL !
best,
jz