This morning before work I swung the coax in this troubled location back to the SWM16. I tried another HR20-700 and it too was having random zeroes on the signal strength screen. I also tried 2 different HR21. Both worked just fine. This makes it 3 different HR20-700 with this issue at that location. Receivers without problems at this location include an HR22, HR21, HR23 and I had n HR20-100 there before its hard drive died.