[Capt. Apparatus]

If you look closely at the tone switch the wiper ground three contacts at a time. So only the center position is the only one that is not connecting any tone compensation parts into the circuit. The first position should give you some bass boost. The 2nd will decrease the bass boost. 3rd will give you very bright highs. 4th will cut the highs some.
Terry

Thanks Terry! I'll double check my wiring over the weekend and give it another listen. For the control itself the fourth position you're talking about is the one with the single cap on it correct? When in the cabinet this translates to the most clockwise position, and how it was before the recap if I recall. 

Of course there's always the possibility that my ears are just shot these days and everything's just fine