Poor connection instrument plug

Soldering the base of the pins to the copper trace will usually do the trick. However... the pins and the copper need to be shiny clean. Here's now to do a great job and do it at low cost. Remove the pcb from the instrument cluster housing. Using a fine brass wire brush, lightly brush all around the pin and it's base to clean and brighten the metal surfaces.

Then make a paste of Bar Keeper's Friend powered cleanser and water and brush this paste on the pin and the surrounding copper surfaces for a few seconds using an old tooth brush. Rinse off the paste residue by rinsing with warm water and brushing with the tooth brush. The copper and mating surfaces will look brand new. Let the board dry or dry it with a hair dryer. Once dry, solder the base of the pin (s) to the copper circuit traces using 60/40 rosin core "electronic" solder and a low wattage soldering iron. Clean off any rosin residue with denatured alcohol and a Q tip.