Before it goes to the scrap heap or something, anywhere to buy this one piece? Extremely blatant problem AFAIK. A key quit responding when its contract underneath tore. Thanks.
Is it worth repairing? It's a 49 key non-MIDI keyboard. As such, I doubt anyone bothers stocking a membrane for it (it's a good 20 years old now). You could try a bodge job yourself, if you really want to save it.
There you go, then! As keyboards go, it's not really got much value... mainly as I pointed out because it's more a toy than a professional instrument. If it had MIDI, it might at least be useful as a cheap controller. If you're going to dump it, there's half a chance you might find some useful components in it if you like tinkering with electronics, but I don't think there'll be much of use, really.