The early IBM Model Ms used bent wire stabilizers instead of the post-and-guide setup.  They have a noticeably better feel than the post-and-guide type.

The wire stabilizers were on both Shift keys, Enter, and the keypad Enter and + keys.  You can also swap the Model F wire-stabilized Shift keys onto an M.

The barrel plates for all of my later Ms still had the (unused) hooks for the early keys, but they're all fairly early Ms.  If you decide to try wire-stabilized keys, pop a Shift key off and make sure the barrel plate has the hooks; I've never personally seen one that didn't, but if IBM (Lenovo, Unicomp, etc) ever replaced their tooling later in production, I don't see why they would go through the trouble of providing them if they weren't using wire-stabilized keys any more.

I bought a tiny bottle of "bicycle dry chain lube" that I use on the posts of the boards I have that use them.  Most of the dry lubes are runny like water; I recomment putting the lube on a Q-Tip or makeup swab and rubbing that on the post to prevent a mess.  More lube isn't necessarily better lube.

bump

where is rukia