I recently picked up a pair of the "large" Advents at a Salvation Army thrift store (20 bux the pair) with advanced speaker rot. I Googled "advent refoam" and ended up ordering from www.simplyspeakers.com. I called to verify the correct part, the guy was very helpful, and had the parts in 3 days, for $26.95, including shipping. I was able to refoam both woofers in about 2 hrs . So hats off for a supplier that knows his spares (and vintage speakers).I've tried generic kits, and having the correct stuff the first time was a pleasant change.
If y'all like to pick up forgotten/nasty looking old speakers, this guy is the one to call.
Larry Acklin