Fixing and setting up friends Thunderbird bass, im trying to sort out a grounding issue, theres an audible hum unless you touch the metal/strings.

Ive tried re-soldering every ground (bridge, pickups, each pot, cavity, jackoutput, but that didnt fix it.

Next i bought a new output jack, still no fix.

Then i removed all electrics, covered the cavity with aluminium tape, tested it with a multimeter to ensure it all connected, then reinstalled the electrics, soldered the pots (ground) to the cavity foil, tested all connections with multimeter and STILL a hum.

My only idea is that perhaps the Bridge ground isnt connected properly (multimeter detected some resistance).

But, ive tried crocodile clipping from the jack shield ground to the bridge and no fix.

We're playing a gig in less than 48 hours so need a fix now!!!

(Note: I also did the same procedure on my gibson sg, (which had a similar hum issue) and now its silent and works like a charm.

Please help!
Did you shield the backing plate for the cavities?

Also, how did you manage to solder to aluminium foil?
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yeah shielded the plate, i didnt solder the foil, just made sure there was a connection via the volume and tone pots. but it all tests for a good signal.

really am stuck, unless its the pickups somehow? might try and replace all the pots today and do a total rewire, but its a pain in the ass.