Stove is 4 yrs old. Did a total clean last month of the blowers, vacuum tube, auger case,4"vent pipe, etc. Great flame on # 1 or 2 with a mag of 1.3 as per spec. However - When setting on #3 it will burn fine for 20 min, then the flame will go out as though the unit was shut down. The daughter board shows a constant red on #3, the green auger flashes at proper interval but the pellets do not feed. Both blowers stay on as if in regular shut down. Direct AC across auger and is fine. Jumped the vacuum switch, exhaust temp sensor and the hi limit switch Individually and all at once. Same issue. Pellet pot has just ash not a build up of pellets. All I can figure is motherboard - this is the original not ver II. ANY IDEAS.