Hello all.
My TV remote control was working poorly, with very inconsistent and/or poor performance across many buttons. I pulled it apart to clean it and found that the rubber button pad and the circuit board were wet. To me it looks like the rubber has hydrolysed. The 'wetness' was oily.
I spottested a few solvents for cleaning, using cotton buds: ethyl alcohol, then isopropyl alcohol, then CRC Contact Cleaner. None were particularly good. My good wife found this thread, which suggested washing the rubber several times in warm (it was hand-hot) water and detergent. Three washes and rinses and the rubber is clean. I dried it with wifey's hair dryer. I cleaned the circuit board with IPA a few times and vacuumed and brushed out the shell. Reassembly. It now works like a new one.
Thanks for the suggestion to wash the rubber in hot water and detergent.