Is my T40 wiring correct

Hello!!

I bought a T40 3 years ago, and now I decided to post here a question:

So, my T40 was made in 1980, and works like this:
- Tone knobs from 7-10 activates the single-coil mode on both pickups;
- Tone knobs from 0-7 work as…tone knobs!;
- Volume knobs work as they supposed to work;
- The same for pickup selector;
- The same for phase selector;
- The only “strange” condition is that I’m able to have one pickup on the circuit when the pickup selector is in middle position and one volume knob is at 1 and the other at 10. The sound is similar to what I would get if the pickup selector was selecting only the pickup at 10, but I get less treble (it’s more muddy). But that’s a pretty useful sound! However, on a paralel connection this shoundn't be happening - with one volume at 1 there shouldn't be no signal at all.

Is my T40 wiring correct?
What I'm missing in terms of performance?