While we're on the subject of changing pickups, I have a '78 Ibenez Les Paul copy and one of the pickups is dead.

I'm not a techy so I don't know which one it is.

It's the pickup that is active when the three position toggle switch is in the down position.

A friend gave me a Jackson humbucker from his guitar to put in, but I'm not sure how to tell which is the bad pickup.

Hey, I just play it, I haven't messed with the insides yet.:D