signal comes and goes local hd channels

[hornhooker]

I just had the new directv slimline dish 5lnb and hd20 receiver installed. The problem is I receive all HD channels I am suppose to and very crisp. But my reception on only HD channels from local station has progressively gotten worse and now I am getting no signal. I have had the installers come back and look at it and everything seems ( as they say OK ) .I even had another installer come look at it with the same results.. I watched them go thru the set up and it seemed to me they were more interested in the 119,110,101,signal strength. Is it correct that the local HD channels come thru 99 and 103. My dish has not moved, yet the problem has continuiously gotten worse. Can you help me . I have two of the slimline dishes because I use one with my RV . Is it possible to use one dish for the channels I am receiving good and then use the other on just for 99 and or 103b. Is there a switch that will allow this...My location is Middle Tennessee 37101