Greg - I had similar problems with mine. Kept sticking no matter what lubricant I used. I got fed up and bought a new one. They're cheap and easy to install. Ever since, I've had no problems. Considering the price of a new antenna motor, I'd just replace your mast. These things fit together very snugly and I think even minor kinks and dirt can really jam them up.

__________________
Chris
2007 E550 4Matic - 61,000 Km - Iridium Silver, black leather, Sport package, Premium 2 package
2007 GL450 4Matic - 62,000 Km - Obsidian Black Metallic, black leather, all options
1998 E430 - sold
1989 300E - 333,000 Km - sold
1977 280E - sold
1971 250 - retired

"And a frign hat. They gave me a hat at the annual benefits meeting. I said. how does this benefit me. I dont have anything from the company.. So they gave me a hat." - TheDon