Looks to me a bit like an electrical loom, not a drive cable - maybe a bad picture. If the seat will still go up you may get enough clearance for a spanner by using that moror. In any case you will have more space under the seat to wind the place where the broken cable is. You will need to make 50 or 60 turns to move the seat and you have to keep the seat rails 'together' or the seat twist will stop you moving the disconnected part of the mechanism..
Good - Fast - Cheap: Pick any two.
3 x E32 735iL (Alpine White, Glacier Blue & Kashmir Beige); 2 X E38 735iL (Oxford Green & Alpine White); E53 X5 4.4i (Pearl Beige); R50 Cooper; R55 Cooper Clubman (Both Pure Silver).
E38 Parts Car
E21 318i; E23 735i; E30 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i
I've just changed my wiper blades and now my reverse lights don't work. Should I change my fuel pump relay?