I'm betting the reason the guy who gave it to me stopped using it, is because it was draining
batteries sitting. It discharged a battery extremely quickly, so I put the battery in and locked out the button, it was putting out about .1 volts that way.
Took it apart, and found a bur on the contact for the button. Must have been just touching the battery. Took it apart, filed the bur off, and put the battery back in, and now it's 0 volts until I push the button.
Not a bad deal for a free mod.