The culprit

This little $355 (dealer quoted price) part has a selonoid (or a small motor) in it and when you insert the ignition key into the switch, turns a small gear which pulls on some levers which unlocks the steering wheel, the ignition switch, the shifter and some other things.

It's a bit too complicated for even itself evidently. Mercedes has redesigned the part 3 times in an effort to make it more reliable. This part number is the newest revision.

the new part

When the selonoid (or motor) quits working it locks everything. It's an anti-theft device but when it goes bad, it won't even allow the key holder to start the vehicle. Because it stops working in the locked position, the part cannot be removed without actually breaking the housing and releasing the gear & lock manually. The mechanic broke it with a chisel and a hammer. The result can be seen in the picture above. Others have taken a Dremel tool and ground a hole in the housing to get at the locked gears and pin. Notice the round black gear is plastic and the worm drive gear is metal? That can't be a reliable combination? I wonder if the new part has both metal gears in it? I sure hope so. You can see the Mecedes Benz name stamped into the old part. The mechanic said that the only thing is made by Dodge on this Winnebago View are the badges. He said everything else is Mercedes.

Part number and box. Mouse is for size comparison.