Well, after I replaced the changeover switch with a new one, Voila! both my fuel gauges now read Full when the tanks are filled up. With the old switch, a full tank would read anywhere from 1/2 to 3/4, but never full. I can only assume that a resistance buildup in the old switch contacts was the cause of all the wonky readings I've suffered with for all these years. So, if your readings are off, try cleaning the switch and switch connecter contacts. Ian

 

In addition to cleaning the internal contacts and the P&J contacts, I found I had to tightly wrap plastic zip ties around the assembled switch to ensure good contact with the P&J.

Bill