Update: I have left the G68 powered up for several days and retaken the measurements at the outputs. There is no AC or DC voltage coming from the outputs.
The G68 has not frozen up since I removed half the circuitry and left the lid off. That is consistent both with the heat theory and with the bad PCB theory.
The G68 has not frozen up since I removed half the circuitry and left the lid off. That is consistent both with the heat theory and with the bad PCB theory.