2012 comp stick control bar .
to replace centre lines.
side 1 remove bungee(safety) ring point below bar( this is figure eight through ring)
then un wind centre line bungee from centre line ( the other end) of side 1 above bar .
centre line then pulls out through the top of the swivel( 2 small stainless posts) . you feed the new one in from the top and reverse process to reassemble.
side 2 . pull little black tab below swivel out(Down) , undo figure eight ( this expands knot so it does not pull through) pull centre line through the top of the swivel , replace with new line and reverse process to reassemble. centre lines are both the same and are heavier than rear lines? 350 kgs i think.
Wondering how the lines were worn? I have used bar heaps and the front lines apart from some very minor chafing where they wind up are as good as new ? hope this helps.

my old octanes were one line bars (5 lines)