BTW I learned how to remove the parts from this video by an intrepid person who did his own tear-down:

Trying to FIX : Faulty Apple Keyboard Model A1243 purchased on eBay

https://youtu.be/zxiPxyLF8p4?t=2408

I am trying to replace just the silicone cup/spring of a key. I managed to remove the key cap and scissor mechanism but the cup is trapped beneath an unremovable plastic membrane. I could probably cut the membrane at the top leg or two bottom legs, leaving top or bottom attached. Has anyone successfully done this? Here’s what it looks like with tweezers inserted under the membrane:

https://i.postimg.cc/SNVwtHCd/IMG-1506-C...