WARNING: As time passes we are seeing more and more ignition lock failures on 123 and early 126, 201 and 124 chassis models. If the tumblers in the lock fail you can find yourself stranded and it can be expensive to get the car towed and the lock replaced. If you change it before it fails it can be inexpensive and relatively easy to replace. When your key starts to "stick" and takes effort to turn it on, get it fixed BEFORE it completely fails.
Problem & Solution
Common among these chassis:
We have found that one of the main reasons for early failure of these locks is putting too many keys on your key ring as pictured. The extra keys add weight and jiggle the key in the switch assembly as you drive. Over time this will wear out the tumblers inside the lock. Get the ring that will allow you to disconnect all your other keys from your Mercedes ignition key. Only drive with one key in your ignition switch!
Also, the regular use of a good quality key lock lubricant can help reduce tumbler and key wear.