keeping your eagle sonar units sealed?

I have been happily using my cuda 242  (I have a 245 ds rigged up more portably too), but last trip some condensation appeared on the screen, 

I got the unit all dried out, I think it is fine, but I noticed the gasket looked like it was not as compressed as it should be, especially on the bottom of the unit, and I think when I hose off the yak and the sonar unit head too, some (fresh thank goodness) water got in there.

I don't have any torx driver bits to try and tighten the screws there so I just ran a bead of marine goop over the gasket and around the whole unit.

anybody got any advice on keeping this thing water tight? does anybody ever mess with those torx head screws?

btw, I pretty much never disconnect my head unit and I have left it connected with dielectric grease in the connector and it appears to be corrosion free after a couple years of use.

John