There's lots of info about this fault. It's common with this unit. The heat management inside the unit is poor and causes the amplifier output transistors to detach from the circuit board.
Resolder the pins and you'll be good for another year or two.
The fan stops rotating when no sound signal is detected (a nice idea to minimise the distracting noise). However, wthout the fan going, the temperature climbs and cooks the solder joints. Switch the amplifier off when not in use and you might get a few extra months out of it! I've put some extra heatsinking on mine, and I'm now trying to modify the fan control circuit to allow it to rotate slowly when the unit is idling.
Good luck.
Charles West
May 2008