For the benefit of new members to the JBL 4343 - 4344 - 4345 space l have posted descent images of JBL drivers with original cones, reconed driver, refoamed surrounds of a reconed driver and compression driver diaphragms. I don’t have JBL 2121H here at the moment but will post an image one at a later stage. I will see if l can post impedance curves of the woofers.
The refoamed drivers were done by a business called Speaker Bits. I don’t recall the circumstances as it was a long time ago.
I will ask Edgewound if he wishes to comment on the work and what 43xx buyers should look for before and after purchase.
Image of refoamed 2231A driver with a JBL 2235H recone kit by local loudspeaker repair specialist.