I have a 6131 with an 18" dish containing one LNB each for 82 and 91, and an sw21. After several weeks of getting near 100% signal, I have been experiencing signal loss that appears to be getting worse. Its at the point where 91 comes in infrequently and 82 almost not at all. When they do come in intermittently the signal jumps to near 100%, then drops to 0. A techie friend checked the signal at the dish and said that it is very strong and that the dish did not require realignment. Checked to see if it would work on an old 3100 receiver, but that too had problems. We also changed the SW21 thinking that it might be the problem, but to no avail. Thought about replacing the LNBs, but it doesnt make sense that both should go down. Not sure what else it could be. Any suggestions are welcome. Thanks.