New proud owner with a tone/pots question

Hello all,

I'm the proud new owner of a 1980 black/black pickguard/maple neck T-40, and a new member of this forum.
I have a simple question: are the tone pots on the T-40 supposed to change the sound progressively, or act more just like coil splitters upon reaching 7 on the dial?
What seems to happen on my bass is just that: no change in tone at all until you crank them up to 7, then the sound loses depth and a lot of volume. No further change until the end of the run.
I appreciate that single coil is going to sound thinner than the humbucker sound, but what I get sounds somewhat dodgy. Faulty components?

Now I love the sounds you get from keeping all the pots to max and playing with the pickup selection and phase switch, but i am under the impression that one of the greatest strengths of this bass is its versatility and abundance of different tones, hence my question.

Cheers,
Marco from Edinburgh

With original wiring you are supposed to have full humbucking at zero and single coil at 10 and a gradual change as you rotate the tone.

It seems I have a problem then...
I opened the cover again, and everything looks fine, no loose wires, components match and soldering is neat and sturdy.
It had a custom made pickguard fitted and then removed at some stage of its life, I wonder if something gone wrong then, since the electronics are attached to the pickguard.

I wonder if the tone pot is going bad?

I found the schematics for the T-40, and I compared it from what i saw in the bass itself. There are no simple resistors in the schematics, but there are two in the bass. I reckon someone done a mod on it, with good soldering. I'll double check, and then take it to a tech, as I can't do the soldering in my living room or kitchen, wife would go spare!
I'll keep you posted.

Very interesting development. Keep us posted.