Temp. gauge is pegged out to max

[Southpa]

I've been thru 3 mechanical gauge/sensor setups so far and decided to thoroughly investigate why the stock electrical gauge /sensor setup doesn't work. The mechanical ones lasted maybe a year each, crapola.

OK, there are no problems going from the sensor to the gauge. I checked for continuity between the end of the sensor wire (dark green) to the back of the gauge and there is current flow. So what is the roundabout route that takes me back to the sensor in the block, via ground straps etc? Are there supposed to be any wires attached to any posts on the back of the temp gauge? Mine doesn't have any. Or is the rest of the current flow supposed to go through the circuitboard/grounding system?

Either way the needle in the gauge is waaaayyyy over to the right whether the sensor is hooked up or not, that means infinite resistance, lol, no current flow. The loop is broken somewhere.

Oh, btw, the engine runs fine NO overheating problems or anything like that.