Help, topre slider won't stay in place

[kuantae]

I opened up my Realforce 87U so I could remove its domes. After doing that I didn't notice anything off with the sliders. A few hours later, I decided to remove the keycaps so I could clean them while my board was disassembled, might as well ya know. However, after removing the keycaps, I lifted the plate up and the slider for the left ctrl key fell off.

I do know that the 87U's lctrl slider is different from the others, it's orientated differently and it looks different. But even after I put the slider back in the housing, it won't stay in place. It keeps falling off when I lift the plate up.

Here is a video of it:
https://drive.google.com/file/d/16KHAcD81BZ1nfa0xJZ_9mnzytQ4-0aDW/view?usp=sharing

Any ideas how to fix it? Thanks!

[Dr-lipschitz]

assemble it upside down. put two books or something on the sides of the pcb to hold it up. put the conical springs and the rubber domes in the cavities of the slider, then put the pcb on top while it is upside down and screw it in.

[kuantae]

assemble it upside down. put two books or something on the sides of the pcb to hold it up. put the conical springs and the rubber domes in the cavities of the slider, then put the pcb on top while it is upside down and screw it in.

That's what I did when reassembling the board, worked fine. However, is it normal for the slider to have that issue? From what I understand, the LCTRL slider doesn't have the little notch thing on top like all the other sliders in the board do. What could have caused it to come loose?