I am aware of some problem spots around the country and you could be in one of those. It may be one or several issues adding to the degradation of the signal. As stated by some one else are there any trees that since have grown to partially block the signal? I think you may need to look at several things individually. First. Did you purchase the equipment yourself? If not then contact DNW again and request to speak with a senior tech or supervisor about the
installation.
If you purchased the equipment yourself then there are a few things you can check. After checking the site lines, how long are your cable runs. If any are over 200ft. then you can put an in-line amplifier at midpoint of the run to help. Remember you can only amplify what you have.
If you are good there then try putting the old receiver back on and see what you get. If you have a signal strength meter or know someone who does check the signal strength right at each dish. Inspect all connectors to see if they are tight and well fitted.
Basically you want to isolate each componant and check them. The dish and lnb, the cable, the switch, the receiver, the television.
If everything checks out then you might be at the fringe of a weak area. If you do find problems correct them on at a time. Sometimes a weak signal can be cumulative between bad connections, slight out of alignment, some branches and long cable runs.