Electronics and salt water do not mix well. Although the gear on this boat was advanced for its time, Furuno ended support/repair service for this model of chart plotter/radar almost 10 years ago. The first step was to move the working unit from the nav station. However, this would require rerouting the network and radar cables.
So, the easiest solution was to purchase a replacement on eBay. Although this model is roughly 20 years old and has been out of maintenance, many working units are still available. It still provides all the useful functions. I also added a connector to the bow-thruster control (rather than having to cut the wires next time the NavPod has to be opened up). Finally, I raised the position of the NavPod 3/4" so that it does not sit directly on top of the compass.
Eventually, we will replace all the electronics. At this point it works.