One of the housings are for a slider to have a horizontal slot for the keycap (the left CTRL). I needed to pull it out of the RealForce 87U to use in the RealForce 104UB so that I could use the green keycap for that key. Now I have a switch housing that doesn't fit in the slot on the frame of the 87U. It is a square shape except for the lower right corner, (looking from the front of the keyboard), which has a flat corner (like it would look like if you folded-in the corner of a square piece of paper)
So I tried filing down the corner of the housing and I was able to get it in, but now I realize that corner is still going to be a problem, as the switch hits it on the way down and the key doesn't extend all the way out.
So the options I see it are :
Find a replacement housing somehow
Find a way to cut that small corner so that it is square and the slider has room to slide
