Thanks much - I do have the plastic decoration panel off and the knee pad so that I have a good grip on the hardened collar. After much research, I have come to know one thing and have hunched another:

Realization: There are detends on each side beyond the one clip (near the base of the collar) that actually release the hardened cap. Important: The 300e is different than all others. Since finding this out (I would love a photo of it) and before finding this out, I have worked aggressively with the identical tool called for - with no help.

Hunch: Much of the tumbler is still between #1 & #2 position, so though I can get my tool in, because the forward portion of the tumbler is broken from the rest, I'm wondering if my cylinder and cap will not release because the switch housing for the tumbler is somehow keeping everything in place until I get the balance of the tumbler to completely to pos #1.

This is all specific to the w124 (my 300e).

I did eventually find a post where someone had the same struggles as I did, and it was the detends beyond the clip that were stuck.. I've worked too hard at this to think that is what I have - anyone with 1st hand experience able to prove my hunch right?

Thank again & again.

Ken (mark's dad)