Commodore PET 2001 Chiclet Keyboard Repair

I am working on getting a Commodore PET 2001 Chiclet keyboard working again. Some of the keys were not working. So I disassembled it and cleaned it. But some of the keys still didn?t work properly. I noticed that some of the keys had something metallic on the bottom of them and others didn?t. It appeared to be random. I talked to some friends and they seemed to think that that the rubber in the keys is a sorta conductive silicon. My suspicion is that this silicon becomes less conductive over time or is not reliable to being with. It seems that the previous owner had fixed some keys by adding some metal to the bottom of the keys. I think it is ordinary aluminum, but I am not sure. When I replaced one of the keys with the thin metal on the bottom to previously not working key, then it worked. My plan is to put this metal on the bottom of all the keys so that they will all work and be reliable. If anyone knows what kind of metal it is and where I can buy it, then I would appreciate it !