I have four blown JBL 2123's.Where the foam which was on the pole piece has rotten and got stuck to the voice coil (voice coil rub) and the voice coil had overheated. I managed to source some rare genuine E110 recone kits at a cheap price to recone to E110 due to 2123 re-cone kits expensive price here in the UK.

Is there any substitute for the foam that does not rot away?

Thanks