From your link, it appears that the bolt that goes in the seat rail to fasten the wire is NLA. I will look in a junkyard for this part.
What I am interested in knowing, is the mechanism which holds the wire tight (and subsequently moves the adjuster) inside the black wheel on the floor or is it in the b-pillar adjusting device?
Is it part no. 9 in the b-pillar or is it part no. 17 on the floor, from your link?