Barry,
I wonder if some of the resistors on that board are out of tolerance. There are ones that should be raised in wattage. Ones to the E and C of the outputs should be 1/2W with a few others that 1/2W is advised. Some models of the boards have a 430 ohm 1/4 resistor that is usually hot to touch if not already discoloured. That one needs to be 1W. The 7704A board does not have this resistor.
Mark
