I agree with you, echan, that the action is an important part of the kinesthetic  typing experience and what characterizes the "action" is fascinating. You did something analogous to adjusting spark plug timing and I'm interested what effect this had on the feel, but my hunch is that most of action is inherent in the design of the linkage and cannot be modified.  Throw length is one variable and a second is the way the linkage handles kinetic energy. A satisfying action stores energy on the down stroke the way a baseball bat stores energy as you swing it, so when the bat meets the ball (you hope) most of the work is done by the bat and not your hands. The reaction of the bat on your hand as you swing it gives the satisfying feeling of swinging the thing!  Type actions are more complicated than bats and more like piano actions (that is, by the way, both the term of art for the physical linkages that transmit finger stroke to string and for the feel of the thing to the finger).

I have now exceeded the maximum allowable length of connected though for a Twitter age post and the gods are rumbling in displeasure! 

One of my favorite actions is the LC Smith Secretarial - it has a long stroke and when you get up to speed the thing seems to fairly bounce under your fingers - and one of my least is Royal Futura, which does not give me the feeling of accumulating energy at all but feels like I am slamming the type into the paper with a rigid finger extension. At least on the particular examples that I tried.

Back to the opening-post about the Olympia SKM...

Found some photos of a SKM.

It looks like it has that special key-top (for horizontal single-spacing to double-spacing) that showed up on SG1 and SG3 machines as well.
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I was able to locate and add this 1968-made Olympia SKM to my collection back in 6-2024 or so.

Lovely machine on which to type and quite the "looker" as well.  I keep this one on my daily-grab book-case next to my desk.  Makes it easy to grab some of my favourites out of the normal use-rotation schedule.

I added some "Leafy Green" satin-finish colour by Rustoleum to its ribbon cover .
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Yes, The SKM is a relatively rare machine.  Effectively an SM9 in a larger case masquerading as an office typewriter.  My theory is that Olympia looked at the Adler Special and thought that they might like a slice of that market too.  Problem was, the Adler Special didn't sell that well either.  There wasn't that much call for an industrial portable.

Back to the topic of the Opening Post No. 1 of this discussion.

I have five (5) Royal Futura 800's in my collection.  I really did not like how you had to open the ribbon-cover to change ribbon-colour selection.

I made the modification (shown in the photos below) on all of my 5 machines.  One this machine, I used a spare lever from an Olivetti parts machine in my stash.
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