I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

If it is physical damage to the speakers, possibly torn cones, then a parts-only matching playbar off the used market would be an option.

Not sure what Sonos will do for you on a replacement since you opened the system before calling them.

(Note to other folks seeing this: Call First!)

These are custom drivers. I doubt that parts are available on the open market and SONOS does not offer repair services or sell parts. There are some 3rd party repair services available in the UK and EU.

You may be able to reattach the cones or purchase an inexpensive unit online and swap drivers.