First things first, double check the instructions...
http://www.winegard.com/kbase/upload/proper_phasing.pdf
http://www.winegard.com/kbase/upload/1450291.pdf
I did not spend a great deal of time looking for the 7696 documentation (it was not in plain view on the Winegard site). Still, the phasing lines need to be assembled correctly. If they touch the boom or one another, expect very poor results.
The balun box also deserves close examination. Any possibility of damage due to over tightening the coax connector?
If everything is assembled correctly, location, location, location... Dead spots happen, move the antenna.
(No, I don't think that antenna has excessive gain in your situation.)