Thanks Simon;
there's a procedure on the American forum here
At same forum I remember there's a difference between pre-95 and post-96 LS400s in that older cars (I think) use motors on the retractors whereas newer cars use a solenoid. As I understand it,when the seat belts are not plugged in, there's power to the solenoid which has the effect of engaging a high tension retraction spring. When the seat belt is plugged in, the circuit is broken, the solenoid drops out, and a low tension spring acts on the retractor. So a possible cause is that the solenoid is not receiving power when the seatbelt is unlatched, the solenoid has magnetic inertia and thus is not activated when power is applied, or the mechanical retractor assembly is gunked up. I haven't had time to pull my car apart but unless I am advised otherwise, this is what I propose to check out
TIA ... Greg