Thanks Rob. Like I said, suspect prob is anim/script issue. Just haven't got round to checking as been on other work. And was secretly hoping someone might have said "I know exactly what prob is". But when have time will go through them again.
EDIT: well, Defiant bridge now seems to be ok (not crashing) and not getting same 'not enough arguments' console error message on either bridge. But SP bridge still crashing not long after load, although just a blank console this time, and the same Preload Assets msg in console dump. So I figure it's prob with SP lift doors as bridge crashes before extra gets on set and was all working ok before. So I'll try and fix that when get chance.