I have been getting all my HD channels with a OTA antenna above my garage for many years. I get about 70+ on signal on all channels except one. I have always got decent reception on CBS (2.1) in Boise Idaho, but now it seems to have dropped to 0-3%? When I go to antennaweb it shows the same distance and coordinates as all the others that I am getting. Any ideas what might be going on?