It is possible that there is something wrong with the UHF section of the HD 8200U.
There are several tests you can make. One would be to connect to the DB8e, if you still have it, to check for UHF reception. If the UHF reception is good, you can combine it with the 8200 with a UVSJ UHF/VHF combiner.
Another thing you can do is troubleshoot the 8200. Winegard has a video:
How To Troubleshoot a Winegard Antenna Cartridge Housing
https://www.youtube.com/watch?v=TlQk...ule1MX8jCAfvPQ
If the circuit board was defective, maybe Winegard will send you a new one.
http://www.solidsignal.com/pview.asp?p=cb-8269
I think the way the circuit board connects to the wires is a weak link in an otherwise good design.