It goes across multiple amps as well as different cables.
But yea I will look into the others.
Also I cant find a XO circuit for it on google. Its on a plastic plate slapped onto the side of the cabinet. I have to get it out and check too, but the staples etc are a PITA to remove. A circuit diagram may help find what could be the first thing to check, and I may be able to do that without removing it.
I don't have a circuit diagram for the xo either, sorry. But you can easily open the box and draw it yourself, it's not that complicated.
Jamo often uses PTCs as protection. Burnt up PTCs can be a reason for low output, maybe in combination with one defect woofer. I'd suggest you test the drivers first (multimeter -> resistance (Ohm)), then the crossover.
What is a PTC ?
Anyway speaker read 7.9ohm, other read 3.9 or so. In that bad one, 1 driver read 4 Mega ohm while others read 6 ohm.
I swapped the bad driver for a car woofer that fit and did that with both. So now these 2 are both equal and working fine, I'll try to locate the right one if I can, but I am good with it as is. it sounds fine, the original wasn't any great woofer. It was a bit weak 6.5" anyway.