“Common problem”? I’ve been reading this forum for well over 15 years, and this is the very first time I recall this problem being posted.
Likewise, I don’t remember any previous reports. These are custom drivers and SONOS does not sell parts for these units. It’s possible that this is a standard surround that you may be able to replace.
I think that the most practical plan would be to purchase a unit that has failed for another reason and scavenge the driver.
Have you checked any companies that specialize in driver repair?
I’d hit ebay or the like for a “parts only” deal that has failed electronics and a good speaker.
My first ebay hit for “play 1 parts only” had failed electronics and a $50 price.
Personally I’d take the trade-in on the Play 1 and my $50 and get a new speaker unless you really have to have a Play 1.