Restoring rubber keyboard on a logic analyzer

I made a successful repair. Here are the steps I used: As I mentioned, I tried cleaning with isopropyl alcohol, without much success. I realized that I could test the rubber contact points with a multimeter, probing two spots on the surface. The offending keys had much higher resistance or simply tested open. That made it easier to try other options without having to assemble/disassemble each time. I found a spray can of "contact cleaner/lubricant" and tried that. OOPS. Made it much worse. Looked at the ingredients: one is "mineral oil". Ok, so that's fine for metal wiping contacts I suppose, but not for this. Washed the keypad thoroughly with dishwashing soap and water, then wiped several times with alcohol, that got me back to where I was. Then I realized I still have a tube of powdered graphite (the stuff sometimes used for lubricating locks, though it turns out that's not a good idea. Squirted some onto a Q-tip and rubbed the bad contact pads with that. They look shiny as a result rather than dull black. But it works! So that's the answer: graphite powder. I now have a working analyzer again. It will be interesting to see if the graphite wears off eventually, I suppose it might but that's ok, I can just do it again. Thanks everyone for the suggestions. paul