Thanks for the research. I just didn't remember, I thought the cap that actually contacts the cam follower was a nut and then it was a locknut below. But I didn't remember.
And you're right, I can't imagine this amount of spring change, would make a significant difference during the life of the engine.
Have a great day,
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in