Just finished testing all of the op-amps. I've included the results in the attached .pdf. On all 11 of the op-amps, the pin 4 and pin 7 voltages did not correspond to each other; pin 7 voltages were all low. Also, when probing pin 3 of op-amp U300, there was a high frequency noise coming from a component in the power supply area, possibly a capacitor. I'm about to investigate the voltage regulator section. It consists of a LM339D Quad Voltage Comparator and a TL494C PULSE-WIDTH-MODULATIONCONTROLCIRCUITS. Any ideas what I should be checking for?