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Get some Endust for Electronics (or a mild spray-type glass cleaner) and spray it at the sticky buttons. Press the buttons a couple times, then hold an absorbent cloth against the panel to soak up the cleaner. Repeat this a few times. It's about the best way I have found to try and wick out the sticky mess without disassembling the panel. If it persists, the panel in the radio/climate controls/etc will have to be disassembled and cleaned piece-by-piece.