GM Counter fixed

I was looking for a GM counter, Justin gave me two faulty ones he had with the hope that I could fix them. This included one Chinese import detector which arrived with a broken screen, and a GMC-300E plus that used to work but now would only flicker when the power button was pressed. After some probing with a multi-meter and a scope i found that the power button dome switch had some corrosion and therefore had contact and bounce problems, so couldn't maintain a stable connection. As to turn on the counter the power button needs to be held down for 3 seconds, it couldn't turn on. After some cleaning the contacts, it works perfectly.

Again, big thanks to Justin Fozzard, now lots of the hard to source components are sorted.