The problem is not in your head it's in the engines head, the balls on the end of the adjustment bolt are starting to wear out. When you adjust the valves the wear grooves are misaligned and after a short while there to much valve clearance again. The only way to fix this permanently is to replace the adjustment bolts and the rocker arms.

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600SEL '91
300E 4Matic '88
240D '83
280SE '77
350SE '73
The most complex systems can fail in the simplest way.
Contra verbosus noli contendere verbis, sermo datur cunctis, animi sapientia paucis.

i don't believe in the lord! He's never bought me a Mercedes Benz.