Actually it's a 1P21 but it's the same electrical setup only it has two lamps. It won't turn on. The lamps test fine. I ripped the entire electrical system apart and everything checks out. I have full voltage at the terminals where the lamps screw in but, as soon as the lamps screw in, the voltage drops to less than 1v. Unscrew the lamp and voltage jumps right back up to full power. Connect a lamp to a separate battery and it's nice and bright. Connect the same lamp up to the wire from the scope and ground the lamp out on the scope itself and it barely glows. I am completely stumped. The full voltage until the lamp screws in completely confuses me......HELP please!!!! I've been working on this thing for about 8 hours now!!