Fuel gauge only going to 3/4 when grounded?

I'll take a better look at the board connections when I pull it out, as I had to rebuild a few of the pins for the big plug. I hear you on the aftermarket sender quality... I have access to 2 '70s parts trucks, one of them may still have a good sender. When I got this truck several years ago, the bed was off and water had leaked in around the sender (sometimes silicone doesn't quite cut it). I remember cleaning up the sender, but it may have finally succumbed to corrosion.