Hi Matt,
This is the same part used in the RL60. It is no longer available from B&O, nor is a repleacement rectangular foam. Member Dillen replaces the foam with a rubber surround, PM him for details if you're interested (note he isn't based in the UK). B&O did at one time supply a bass port conversion plate but there are mixed reports on whether these are still available too.
I suggest you use the search facility at the top of the page and search the entire site for "RL60 ABR" - this should pull up most of the threads where this subject has been covered in the past for RL60 repair, it will apply to your case too.
Have a good read of those and see if your questions are answered there.
Good luck.
Generally speaking, you aren't learning much if your lips are moving.