I bought a used Jarock guitar (made by Ibanez in the 80s for a Dutch importer), but it has a horrible buzz on both pickups (Gotoh humbuckers). When I touch the screws of either of the pickups or the metal ring around the pickup selector switch the buzzing goes away, so I assume it's a grounding problem.
Now I've checked the wiring with a multimeter and I found that one of the pins of the pickup selector switch has twice as much resistance as the other two pins. I also found that the bridge is not grounded.
What should I do here, should I resolder the pickup switch, ground the bridge or something completely different?