I figured out what the person was and it’s dumb with a dumb fix. There are two small pegs that come out of each key, and the pegs are actually slipping into the hole of each bubble contact. So I am gluing a small piece of rubber around the end of each peg so they don’t slip into the hole. Seems to work!
After putting it all back together, I don’t think it’s actually a conductivity problem. On the keys that are not working right, I can sort of feel the bubble contact engage when I should not feel anything at all. I’m probably going to do some open heart surgery with the keybed outside to figure out how the keys are not setting right in the keybed.