In response to last two posts,the tumbler fails 99.5% of the time. Unkl300d, your are in the .5% group. I have replaced one steering lock assembly in 25 years of running a Mercedes shop. The tumbler actually breaks inside. I would replace the tumbler first based on the 99.5% figure, and then replace the lock assy if the persists.Don't feel you've wasted sixty bucks on the tumbler; you'va just done preventive maintenance. The procedure for both operations is listed in the W123 chassis shop manual under Group 46 which is steering.

Peter
Auto Zentral Ltd.

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Auto Zentral Ltd.