Epiphone Sheraton II wiring curiosity - bridge volume acting wrong

Hi,
On a 1992 Sheraton II.
You'd believe on these hollows & semi-hollows there's very few people who'd try to modify theirs, especially at the pots part, cause it's like working as a damn dentist with the mirror.
But here's some curious bothersome shiznit I ran into when I plugged in my "new" 1992 Sheraton II:
When toggle's in the middle position and I turn the BRIDGE volume down, it actually boosts like if it were in series.
But when the toggle is on the bridge pickup, then turning the volume down works just fine, like, turning it down, even to 0.
What's more curious: sound coming out on the bridge pickup is a little weaker than the one on the neck.
What happened here?
Many thanks ahead!