Hi Goldjazz,
This should be of interest to you and others, plus confirms what Johnlcnm wrote in post # 2 about shorting LF input terminals. It seems to be what JBL actually suggests to do when speaker transport is involved:
"Loudspeaker cones can bounce around quite a bit during transport, and cone damage can sometimes occur because of this. However, shorting the voice coils during shipment will tend to damp out cone movement, lessening the possibility of damage." (note 1)
A picture is attached showing how JBL does it with 1/4" input connectors (first example), but you can adapt it to you particular connector situation.
Having no woofer surrounds in place to hold the cones makes your shipment even more fragile I guess. Good luck. Regards,
Richard
Note 1: JBL Enclosure Information Manual, 1979, P. 21