From Hohner - Historical Guitar Models
'1 single coil J-style + 1 single coil split P-style; vol/vol/tone/tone; bolt on maple neck with rosewood fingerboard; 863mm scale; 24 nickel silver frets; solid alder body; gold hardware; colour: metallic red, royal blue'
If you can send images of the controls and wiring as they are now including the new pot and with the info above, I think it is possible for some of our resident gurus to piece together a wiring diagram for you.
Failing that: BCers Prepared to HelpFix a Bass.
Welcome to the forum.