If the buttons work part of the time, but not all the time, it's probably the sensors. The cheapest way to fix the sensors is to cover a sheet of stencil plastic in copper tape and replace whatever's on there, but a better way to do it is to get a few sheets of steel (make sure it'll conduct electricity; some varieties won't) or copper and use those, attaching with contact cement.
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I used to be active here lol