Been a while!

So I played a Galuzska-built Clapton for the bigger part of a year now and only recently got another Strat, a 56 NOS with Modern Wiring. The spec sheet says the guitar has 250K 10% Taper Split pots.

I plugged it into my Custom Champ today and noticed that the master volume knob seems to have no effect. The sound seems to get slightly fuller when its turned all the way up but not much more happens. Now as I am familiar with the active Clapton electronics, I am not really sure what to make of it as volume pots might behave a bit weird on a passive guitar.

The only thing that makes me think it's a bad pot is that I cannot turn the sound off at all. It's basically always at the same full volume.

It's a completely new instrument, straight from the dealer. I am doing this wrong? Is this normal for these pots and my kind of amp? It sounds great otherwise...

I'd really appreciate some input!