Symptoms: When tuning to many national HD channels, I receive a message that says Searching for satellite signal (771), or words to that effect. Local HD channels seem to be coming in fine. Signal strength on sat 101, tuners 1 and 2, is adequate, even transponders in the 90"s and odd transponders in the 80's. Signal strength on sat 103 (ca) and (cb) is extremely low, in 30's on even transponders and 20's on odd transponders, both tuners. "Signal strength" for swm shows 90's and zeros. From what I've read on this forum, my diagnosis is a bad lnb (sl3-swm), but I'm a hobbyist, not an experienced installer. I'm ruling out misaligned dish and bad power inserter because of the disparity in even/odd transponder signal strength. Have I diagnosed this problem correctly?