"Cooling" problem solved

I rebuilt one radiator that truely needed it. I replaced one thermostat that was probably just fine: twice. I replaced one water pump that was probably fine, but the bearings did feel "notchy."

None of that fixed the warm running problems I was having. The car would regularly register 230+ degrees. Sometimes under similar circumstances it would register ~195 degrees which I would be content with.

I was about to post a thread asking on advice for which flushing agent to use when I decided to check the connection for the temperature guage on the guage itself. As I was pulling the guages out of the dash, the termperature dropped 20 degrees, playing with the wires at the back would get it to swing ~40 degrees.

Now, my question: does anyone know how to run a wire from the guage sender directly to the guage... I ask because it does not look easy with the big round connector that seems to send the signal. Also, which of the 3-4 temperature senders are the one that goes to the guage?

Thank You.

PS- This is the 1979 300SD in my sig.