I drilled a small hole in the column jacket and tightened the offending screw with a phillips screwdriver.

Copy and pasted from Benzworld (Art's thread)...

I was under the dash (driver's side) yesterday replacing the evaporator temperature sensor (which solved my AC problem) and noticed there was no obstruction between the bottom of the plastic steering shaft sleeve and the philllips head bolt that needed to be tightened to keep the sleeve from rotating when using the turn signal. So, I drilled a hole in the bottom of the sleeve just large enough for my phillips screwdriver, inserted the screwdriver, and tightened the bolt! Some details: I used a 5/16 bit. Locate hole center 1 3/4 inches behind the base of the steering wheel at approximately 5 o'clock position when looking at the steering wheel from the driver's seat. This should take no more than 10 minutes. And even better, if it gets loose again it will be a 1 minute fix. Hope this is helpful. The car is a '97 E320.

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1982 300D-T (sold)
1988 300E (sold)
1994 E320 Wagon (sold)
1995 E320
1998 E300D-T
1999 E3204M Wagon
2001 E320
2005 E320 CDI