deskthority

I'm currently attempting to restore a Basis 108 keyboard. It uses the Cherry M8 switch.
http://deskthority.net/wiki/Cherry_M8

The problem with the keyboard is that many of the key caps rock back and forth, when they're supposed to be solid. While typing, if I hit the key straight down and center, then the switch works. However, if my finger hits the top or bottom of the key cap at an angle, then the key cap tilts, with its inside part of the key cap hitting against the housing of the switch, therefore the switch doesn't get pushed down.

Removing the key cap from the switch, it appears as if the stem is shorter that it is supposed to be. Looking at the stem, there are two bumpers back and front that I assume are trying to prevent the key cap from rocking back and forth.
Unfortunately, the key cap inside appears to be too deep, so I'm assuming those bumpers are not keeping the key cap steady because they can't reach.
Are there any tips to improve the design of the switch and key cap?

I don't think there is really much you can do. The open top switches just have a lot of angular play. You could try hunting for some of the closed version M8 that have tops, but the effort is probably not worth it.
Good luck on your restoration.

Actually, I did find M8 switches with the cover. There's an electronics store in my neighborhood that happens to have this switch in stock. I couldn't be luckier.

According to the catalog PDF I found on this web site, the switch in the keyboard is the uncovered model, designed for the 6mm keycap. The switch I found at the store is the covered switch, also for the 6mm keycap. Also, the covered switch has a much longer stem, so with the keycap on top it would be roughly 2mm longer. So I removed the cover off the new switch, and placed it onto the switch in the keyboard. Unfortunately, the stem is too short, therefore it doesn't even pop through the cover.
I think the issue is that the + on the stem is wearing down with age and use. When I place the keycap onto the new switch, it is extremely tight, and won't rock back and forth. The stem is much smaller and thinner than the newer Cherry switches, so that's probably why Cherry stopped making these. If I can find about 70 or more of these switches at the store, I might actually attempt to replace the stem with the longer one, despite having the keys stick out 2mm more.