Replacement start and select buttons for the NES dogbone

[treismac]

Does anyone know of a site that sells replacement parts for the dogbone? I have five of them and one of them has a start button that is hit or miss, making Mike Tyson's Punch-Out rather hard to play. They sit slanted in the controller like the SNES' controller, unlike the original's perfectly straight layout for all the buttons.

[FABombjoy]

If the silicone isn't broken, usually all it takes is a quick once-over with an alcohol soaked swab to bring them back. Have you tried cleaning it yet?