When you have no signals on 101 and 103(c), do you have no signals on the other satellites as well? Next time this happens, try swapping the antenna lines on the receiver to see if the problem moves to tuner 2. If so, there's a problem with that cable. If not, then try swapping the BBC's as well. If that causes the problem to move, you've got a bad BBC. Only if the problem always stays with tuner 1 should you consider that you might have a bad receiver.
Most problems like this are due to loose or corroded connectors on specific cables. If your problem is isolated to the tuner 1 antenna line, all the connectors in that line between your receiver and your multi-switch need to be loosened, inspected for corrosion or intermittent internal short circuits, and re-tightened until snug with a 7/16" wrench. Pay careful attention to wall plate pass-throughs, outdoor connectors, and poorly installed crimp-type connectors.