I've had a 508 PVR receiver for about 6 years now, and it hasn't given me any trouble. Up till last month it was in a cabinet while in use. I removed it and moved it to the den when I bought a 40" Samsung HDTV. I notice today that it has a "fan" on the rear right side. The fan doesn't run (move) when power is on. It may never have worked. Does it (fan) run only when the heat builds up in the receiver, or it gone?