There's a good thread in here about removing the instrument cluster...a search on it will bring it up. It also mentions how to make a tool to remove it.
I've had similar problems with gauges on my MBs (esp. fuel gauge) and have found that the cold solder joint in the back of the unit itself is usually a good suspect, esp. when a "tap" on the dashboard seems to fix the problem...
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