Repair Used Focal Speakers

1st if you can renew the contact with seller, ask if he’s registered this product online for warranty.

2nd if not and he’s still got receipt of purchase(in fact even receipt isn’t needed in some cases) register your product for warranty online with mentioned purchase date.

3rd, bring your speakers to Focal dealer and get them repaired for free.

Tone, so you have 2 woofers in the same speaker that are not operating the same way?  Then it's likely to be a woofer problem, but it could also be a cabling problem. If you can, remove the back plate and look at the crossover.  See if the woofer wires are crimp on or soldered to the board.  Examine the connection in any case. Take a picture of the crossover while you are in there and send it to me.  I want a look too! :)

I'm not sure if you can, but you might be able to reach the woofer connectors. Double check to make sure they are fully on and tight.

As for warranty, any Sopra should be under warranty though, they just came out. :)

With the speaker disconnected, gently move both woofers. See if the "good" and "bad" woofer move with the same degree of freedom. If the bad one feels in any way different, then that’s your answer. Make sure your amplifier is off for this, as amps with negative feedback will resist cone motion.

They should move easily, like pushing into a Krispy Kreme donut. :)

there 1 video on youtube https://www.youtube.com/watch?v=8ajUZ_AJ0es
Man showing problem with one bass driver of focal sopra2,seems clicking sounds coming .

The speaker will be under warranty. There is good advice in this thread.
Happy Listening!