need to waterproof the mount unit

I have had the mount on my 05 Harley Ultra Classic for about a year and it has worked flawlessly until recently when it started to not power up the quest. I thought it was the plug in the back and decided to break it down and discovered the electronic panel inside was corroded and it prevented the lead to contact power with the pin. The panel has blistered and I do not know how much longer it will work. The Quest is the best system (I believe) because it has a battery backup but I think the mount needs some tweaking.