hifi engine

Tannoy 605 speakers

Hi All,
My first request. I have 2 pairs of Tannoy 605 speakers. One pair works fine and is cosmetically good with the exception of a piece broken out of one of the plastic plinths. The other pair work well enough (although the tweeters have lost their domes) but are cosmetically only suitable for the workshop. My query is how do I remove the plastic plinth from these speakers? I'd love to swap the broken one for one that is intact but can't work out how. There are three cover caps on the base, although only one covers a screw and that is into the central spine that runs up the inside of the cabinet. I suspect the plinth is bonded to the cabinet which means it is probably not removable. It might be a job for epoxy filler and a wet winter weekend!
Thanks in advance for any help or ideas.