I had a similar problem in a woofer. I used an epoxy made for rubber. It worked perfectly and I never had a problem with it. My cat had torn the rubber surround. I got the epoxy from Lowes/Home Depot.
JL Fathom repair
I have a JL F112 and the rubber surround has developed a hole in it. I am located in the Portland Oregon area and there doesn't seem to be anyone that can do the repairs....it sounds like you have to ship this massive thing back to JL in Florida for something that should be pretty simple. Does anyone have any suggestions or alternatives for repair that don't involve a return to JL?
Scott