Would like to share a tip here (maybe already known here, anyway I found it out on my own), how to lift off those type plates that stick around the magnet hole on the rear.

In the course of cleaning the debris from these rotten foam filters in the K/E-130 and 140 series, also experienced this with a 2205 recently, I got a tip from a friend to cut off the aluminum dust cap with a sharp cutter, vacuum out the dust and foam crumbs and later glue in a new aluminum dome.

No, I thought, this can't be it. I decided to take another route:

Cautiously I dripped acetone into the circumference of the round type plate and began to gently lift off the plate starting out from the edge, watching for not bending it. The acetone (seems to be the only suitable solvent) solves the glue and feeding more acetone under the loosening plate enables you to lift it off totally. Just watch out to prevent the solvent from dripping into the hole.

With the plate taken away one can now vaccum out the inside from the rear - I did that while feeding the speaker with a low frequency sine (20Hz or even lesser). Also care has to be take to vacuum not too hard and leave a distance between the vacuum throat and the speaker.

After being done you wet the glue residues a bit with acteone and press the label against it. You may take new glue also.

How do others cope with that foam desease? What is the story about it? Is it the sentence of death to a speaker when it got these foam crumbles?

--
Christoph