Bellari PP 555 one tube Pre-amp ....A strange problem

When I turn on my pre amp and touch the top with my hand , it has a loud ground noise.

When I remove my hand from top, noise disappears.

I contacted Bellari Tech and he suggested to loosen screw on side of cover to ground the screw with a wire, which I did.... with no difference.

I removed the wire, and  I touched that screw to tighten it,  it made all kinds of noises...popping...buzzing.

I then left screw half way out. When I touch the top with my hand, the

NOISE is gone !....

I contacted Bellari tech again but he did not know what this indicated.

Any suggestions what the problem could be ?

Thank you