Install a , Antenna Craft , HBU44.
Aimed at about 178 degree magnetic compass direction.
Here is how to aim antennas ,
http://www.kyes.com/antenna/pointing/pointing.html.
Digital Tv tuners can develop -Digital Glitches- that are not cleared out with simple channel scans.
Do Double Rescan.
http://www.wchstv.com/DoubleReScanAlert.pdf.