3 amps at 1.2 volts makes the glow plug glow bright orange. If you don't see bright orange with whatever power supply you're using, it's not supplying enough amperage. At the proper amperage, 2.4 volts will burn the plug out. A single AA battery does not supply enough current to light a plug very well - especially if it's a rechargeable. Try a new C cell or D cell.
It sounds like the glow plug circuit of your EZ Start wand crapped out. I'd suggest a purpose built glow driver with a good/new NiCD or NiMH sub-C cell.