Got a tip today from fellow Geekhacker Phoenix. So.....you don't like the springy twang of the IBM Buckling Spring. Yearn for a soft and quiet actuation but like the precise feel and typing speed of the good ol' buckling spring? Don't feel like messing with grease??
Here are the directions given to me from Phoenix:
I tried a silencing mod on the model m that's easy and actually works.
Use fluffy floss, cut the fluffy part into uniform sections of
slightly less than spring length, hold the spring straight, gently
inert floss sections into the spring, and you are done. The residual
vibration of the spring is greatly reduced. Now the key sounds more
like Alps.
I also tried folding and inserting twice as much (I used a long and
thin piece of plastic to push the center of the floss section in
first). Now it sounds kind of like Cherry brown. It's that quiet. I
also tried using a washer from the wheelwriter in addition to this,
which further dampened the bottoming out noise. Didn't have time to do
it to the whole board, but I highly recommend that you try it. Huge
difference, and key registration is absolutely unaffected (at least on
mine). Should work on the Model F, too. Much less hassle than the
"little piece of foam in the spring near the hammer" thing people did
according to one of the patents online.So floss is one thing that I have a LOT of and in various types.
Enter.......Super Floss!!!

Super Floss is something that I dispense frequently in my office for aiding in cleaning under implant restorations, bridgework, large embrasures etc... The floss has a thin, stiff leader segment, followed by a soft, spongy region and then some stiff, but more standard dental floss.
The spongy region is what you want to use:

Simply chop off a piece around the length of the buckling spring and insert into the center of the spring. That's it. When you're done, it should look like this:

Closer up:

Now the keyboard thocks and the higher pitched "ping" is completely gone. The actuation is somewhat damped in my opinion, but Phoenix didn't seem to feel any difference. Maybe it's because I had some extension of the floss past the uppermost height of the spring.
Now it's quiet, and soft. Difference is NOT subtle. Preference is another thing. I've come to expect the good ol' buckling spring ping. Just seems odd typing on a dampened IBM buckling spring board. According to Phoenix, doubling up on the foamy floss will soften the sound/feel to something similar to Cherry browns. I don't doubt it.
Try it. It's clean, simple and easily reversible. If you don't like it, simply remove with a toothpick or other small implement. I used college pliers to pick out the spongy floss. Use SHARP scissors (I used small surgical scissors) to cut the floss cleanly. Otherwise, the floss frays and it won't simply drop into the center of the spring.
Tomorrow I'll perform the mod on an entire Space Saving Mini and report back.
Fun mod!!! Give 'er a try and post results.
skc