I had a good signal and good quality level (at least 50% on each bar). But some channels would still show "no sat signal".
Taking the connector off the LMB and pointing the cable downwards, loads of water dropped out. Plus, the signal wire (the middle bit) was broken. Cutting the cable back by 4 inches, the outer ground copper turned from black to copper colour. Re-made the connection, all now perfect. The moral of the story is check the cable to LMB for water penetration, even though a good signal strength might be showing.
cumbrian george, June 2008