I just picked up this early 70's Gibson SG pro the other day. I'm noticing a big difference in the output between the neck and bridge P90's. Neck is much hotter and bridge is very weak sounding. In the middle mode its almost a "quack" kind of sound..and even weaker than the bridge! I see that the bridge pickup is missing the cover on the p90. It also appears to be missing 2 screws that should be mixed in with the pole pieces in between the A and D and G and B strings. There are holes but no screws. Not sure if they're important or not. You can see from this link what I'm talking about. http://users.goldengate.net/~jgermann/SGbodycloseup1.JPG (click on pic for supersize!) This is my first P90's guitar so I'm unfamiliar with them. Thanks in advance.