Just replaced my single LNB dish with a 3-LNB oval dish to receive HD channels - also got 2 new H20 receivers. Problem is - while adjusting the dish, I am only able to pick up satellite C. I get 84% strength on transponder 8 - 64% on 10 and 64% on 12. Nothing at all on A or B. Pole is plumb, tilt is set at 102 per DTV (97015 zip code). Any ideas??