Thanks TechWriter
The second illustration, without the UHF/VHF diplexer, is what I'm trying to do. I am using the GM-MP1, and that is why it doesn't work.
I agree with not trying to rebuild my old dish. The 500 you pointed me to is about $20 more than the price I would pay to rebuild mine. I'll toss it back in the barn.
In conclusion, I now know why it doesn't work and what to do to make it work. Dish Network was correct in saying it won't work and "THEY" do not sell compatible components to solve my issue. All they wanted to do is upgrade me to Hopper/Joey.
Thanks to everyone for your help