Quite a while ago I did the silent mod with soft landing pads on my FC660C. Ever since then I've been noticing substantial scratchiness on most of the switches. I can imagine the reason is the keyboard is now super silent, and all other noises have been eliminated, but the scratchiness is so obvious that it's hard for me to imagine it not being there before.
So today I took the keyboard apart again, and the first thing I did was to remove the landing pad from one of the very scratchy switches and test it again. The scratchiness was very much still there, so the landing pad is definitely not the issue. After that I proceeded to apply EK MechLube on various parts of the slider/housing. First I applied the low viscosity grease to the two "legs" of the slider - the scratchiness was still there. Then I applied the low viscosity grease to the entire opening of the switch housing, as well as to the switch stem - again, it did nothing. Then I swiped off the thin grease, and applied the high viscosity grease on all the parts again - still scratchy.
I am not 100% sure where the scratchiness comes from, but from what I can see, the only pieces actually making contact while the slider moves are the slider feet and the little groves in the housing that they sit in. From my observations the slider stem does not actually touch the housing at all, because the feet have too little give for the slider to be able to tilt enough to overcome the gap between it and the opening in the housing. However, it is very hard to imagine that an edge or surface in there could be so rough that not even thick grease helped with the issue. I also tried to grab a toothpick and rub the tip of it up and down around the slider feet and the grooves in the housing and the action felt very smooth throughout.
I'm kind of at a loss now as to what else I can do to make the switches feel smoother. Any ideas are welcome.
