Replace 2420 foam pads?

[Tom Loizeaux]

I've noticed that the foam inside the rear cover on my 2420 compression drivers has deteriorated and becme a little sticky and doesn't "bounce back". How important is the quality of these foam inserts in terms of affecting sound quality? Should I replace these? With what? Altec uses a 1/4" thick felt pad, while JBL seems to always use plastic foam.
Thanks,

Tom