That is the safety magnet. When the pilot generator is lit and you depress the knob this safety magnet remains open (as long as the millivolts from the generator are sufficient to hold it)to allow for the gas to go out and ignite the burner. Up topside of this bad puppy is a red plastic piece that connects to the operator (below it)Right behind that red plastic is the regulator(on top).

Take a look here:Since the black wire goes over to the safety magnet and their are no other wires attached then the coil inside would have to have continuity to hold or it would be bad would it not? That middle screw is bolted to chasis and feeds back to the thermophile. That is what powers the magnet. Note: sometimes that black wire gets cut in 2 and has a high limit added there between the operator and the safety, for a deep fat fryer so that if the oil gets above 550F then the limit kills the power to the safety before the fish house burns down. LOL! Sometimes they add a high limit fuse under the burner on a floor furnace there. Where was I? Oh yeah to bench test the valve you need the Thermopile(Millivolt Generator) and the gas valve (in tact) hook up the pilot generator wires as pictured and press the knob while it is positioned at the "PILOT" mark. Heat up the generator with a torch and press the knob downwards. When the generator heats up then the springloaded electromagnetic coil should stay put. Move the gas valve knob to the "ON" position. Quickly jumper the valve and blow through it to see if it is working. Note: Nothing can be repaired on this valve if it is defective it must be replaced.