Luke 3 hss, hum/grounding problem

First timer here. I just got a mint condition Luke 3 hss, a really fine instrument. Can´t actually wait to come out doing some gigs with it as soon as it´s possible.

From what I understand the single coils are supposed to be noiseless but I have some problem with them having a bad hum.

It´s the kind of hum that goes away if I touch some of the metal on the guitar, like the bridge. So it behaves like a grounding issue but couldn´t find anything when I opened it.

From a quick search I found several threads regarding the same problem. So I wonder if anyone has find a solution? It´s a shame on such a fine, professional guitar otherwise.