Possibly applying some heat, say from a hair dryer, should cause the cone to expand and pop out. I wouldn't think the driver would mind a little heat on it, never tried it myself though.

For tape I would try some house wrap tape, ie. Tyvek tape(red), this is some very sticky tape.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70