Dynaudio Audience 50 spare bass driver

[ashok]

I have a Dynaudio Audience 50 speaker with a strange problem on one unit. The problem started only recently and I'm not sure how it happened.
The bass driver moves freely for the first 1 or 2mm . After that it seems to strike something and produces a rattling sound. The sound is sharp like hitting something.

Since the protective foam at the rear of the driver crumbled away a long time ago , I pushed the cone outward through the vent at the back and felt along the inner surface of the voice coil. I find some material either formed or stuck to it. Might be a mm or less in thickness . What could it be ? Melted glue ?

Anyway is there some way I can remove the cone? What solvent would dissolve the glue that is used.

Alternatively ( last resort ) I will have to replace the driver . Can I get a spare driver from anywhere ? Not from Dynaudio. They are too expensive . That money can be better spent on a new speaker.
The catch is that I have to fix it. The speaker doesn't belong to me - it was on loan !
Thanks.
Cheers.