Temp Gauge Fix Finally (i Think)

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O.K. The easist way to find a problem with a gauge or electrical problem is to have your favorite tool distributor truck come by and attempt to sell you a tools. tell him your issues and let him show you how to use the tool(in this case it is called a POWER PROBE) to find the problem. This is a tool that can add 12v power or ground to the part in question to test. I have a intermittent power supply to the gauge. The circuit board is the problem. I did install a aftermarket gauge to the orig sender and it works fine. I can't thank everybody enough for all the imput and p.m.'s . I need to come up with a circuit board and swap it out. Oh hell i've not done that before, any suggestions. Here we go again. Might trade it for a bicycle. Thanks
Gary

Is this a common prob with circuit boards and should i go new or ok finding a used one?