My speedster gauges were leaking from the front to where water was pooling in them and one of the tachs was acting erratic. I took clear windshield silicone and went around the back side lip of the gauge( the part that touches the hood), and then on the fuel gauge that is exposed the most I ran some around the ring where the glass meets it and then wiped it off, so just the very edge shows, did not want it to look more ugly than it already is.
To dry them out a hair dryer on low for about an hour pointed at the glass took care of it. The boat gauges have two holes in the housing and actually have a desiccant pack inside them for what it's worth so it helped to point the hair dryer at the holes for a while too. Desiccant only works for so long before it gets saturated, then it has to be baked dry again.