tone control question on lakland JO4 (jazz bass)

[JUSS10]

i recently got a great deal on a lakland JO4 and have a question about the controls. i posted this on the LOG but didn't get much input on it. here is what i posted:

i like to bring in the lows to get a fat bottom end but something seems weird about this tone control on the bass. as i role off the highs, it also drops the volume. i would say the volume is cut by a good 50% from full treble to full bass (bass being half the volume) is this normal? is there a wiring fix? i pulled the electronics plate and its all wired correctly. this is my first passive lakland so i can't compare to another. thanks

just wondering if something is weird here or not. i'm happy with the passive tone so I'm holding off on adding active electronics if i don't need them

thanks

Justin