avsjerry:
I tried something a local phile gave me that (to me) smelled like brake fluid and then I tried a skin lotion my wife used (think it was lanolin based).
Also tried re-doping a pair of US made drivers (forget who originally made them as they were marketed under various brands - including Lafayette - maybe Jensen).
In all cases they stiffened back up within 2-3 months, or so, and I gave up.
I still have 2 pairs of Japanese made 4.5" drivers with porous (screen like) cloth surrounds that I have not messed with (the surrounds).
They mated OK with a Gallo TR2 sub set @ the speaker level default of 100Hz and I assume that they fall like a rock @ around 90Hz.
I own/owned "vintage" Stephens Trusonic, Coral, Elac, R&A, RCA, Foster (predecessor of Fostex), Altec and Jensen(?).
Maybe a few others I've forgot.
DeKay