Here is another example of how a small amount of an electronic lubricant/cleaner can restore older electronic equipment.
In this video I'm working on a Cobra 135XLR CB radio. The original problem was it would broadcast a loud AC hum whenever I pushed the talk button on my microphone, and no audio would come through to the person on the other end.
I tried replacing the microphone thinking that might solve the problem, but what ultimately corrected the problem was spraying electronic lubricant in the push switches and variable resistors.

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