Thanks for all of the input. I guess I have tried most of the usual suspects in this situation. If I get too far off axis I loose RF 17 and even the RF 7 counterpart, which TV Fool is not showing. KVIA plans to move from 7 to 17 but have been running both for about two years.
I tried 6db attenuators up to three of them equalling 18db, of course lost several stations at that point.
Yes, there are trees! There is a row of pine trees about 100 feet from the antenna, which it must "look through". However, they are rather thin, under-irrigated West Texas trees and I have the antenna in a position that best looks through them. They have not changed much in the 12 years I have lived here which would include the pre-digital era and my first HD set top box (a Samsung SIR-165).
And, no, unfortunately I can not cut them down. They are meant to shield the trailer park from some of the strong westerly winds.