Try using a valve grinding compound on the end of the allen to cinch up any play. Tell the techs to use a new (ideally) allen.

DO NOT try to use the steering lock to hold the steering wheel. Best to have several people isolating the steering wheel from turning while someone, as stated above, uses a long breaker bar.

Several stout raps on the bar prior also helps.

Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)