Ted, we have a 2004 2499, too. I have not noticed any leaks up front around the window. If it's actually leaking around that window, I would suspect the seal between the window and the body of the coach.
Camping World sold me some putty tape in a roll that I've used on my old popup. It's what I would use if I needed to re-seal the front window on the Sunline.
We've camped at Henderson before and YES, the sites are nice, the beach is GREAT. Of the three Florida State Parks in that area, (Grayton, Henderson and Topsail) we like Henderson the best. The only advantages Topsail has is full hookups and concrete pads. Remember, the Bass Pro Shops is closer to Henderson!
We've got one of the digital converter/tuner boxes for our coach, too. We have seen similar results to yours when using it. I've considered replacing the head unit on the Winegard antenna with the newer model (model III, supposedly designed for digital & HD), but this add-on is supposed to be designed specifically to enhance the UHF digital signals and is less costly than the replacement antenna head unit. We may try one of these Wingman add-ons first.
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Dave & Cindy
'99 Chevrolet 2500 ext. cab (2WD)
5.3 liter V8, 3.73LS, Prodigy, Hensley Arrow
2004 Sunline Solaris SE T-2499 #5527