Noisy Used Ibanez (Need Help!)

[Codymb]

I know what you're thinking "Oh boy, another thread about an un-grounded bass. This will go nicely with our collection of 1,000 other threads just like it." But let me reassure you that it's not that simple.

I recently bought an old used Ibanez Gio as a sort of "fixer upper" project. It's not in the best shape but it plays well. It's an older model, from maybe early 2000's. I plan to give it a make over and maybe put some newer better hardware on there and use it as a back up to my other Ibanez basses.

The problem is that I'm getting a lot of noise out of it. It's that awful buzzing that goes away when you touch any of the metal that we all know and hate. When I first got it and plugged it in I thought "Great, it's not grounded" so I took it apart and got to looking for the problem. Here's the interesting part, I couldn't find a single issue. The ground wire is touching the bridge, the wires are intact and connected, the cavity is shielded, there's no outside interference, it's not the cables or the amp because it's only doing this with this bass. None of the usual suspects. I'm stumped.

Maybe I'm overlooking something obvious here but I don't think so. I'm not the sort of person who likes to take instruments to the shop for repairs, I'd rather do it myself. So if anyone has any suggestions I'm all ears.

TL;DR - My bass buzzes like it's un-grounded, but I'm pretty sure it's all wired correctly. What could I be over looking?

Thanks in advance, CMB