If the stove is the same as the one in the link ...then you have a milivolt powerpile, not a thermocouple. When you said you measured the voltage from the two wires that confirmed it. Anyway, I assume you got the .5 - .6 v with the pilot lit. powerpiles generaly put out ~750 Milivolts (.75 volts). The gas valves idealy like that amount but have been known to operate on as little as 300Mv. yours should operate at 500-600 with no problem. At this time I would suspect a faulty gas valve. Do you have a schematic for this unit you could post? When you said this "The electronic system isn't sensing the thermocouple right and it's shutting off the valve once I let go of the button for the pilot" it has me wondering. Normaly the powerpile is hooked up directly to the gas valve. One wire to the TP terminal and the other to the TP/TH terminal which then routs power thru the other safety devices and the thermostat (if equipped) and back th the TH terminal