Not trying to hindsight anyone...
I can't tell from the pics if those wires sit in individual tracks or a tunnel.
Just an idea,
1) Tape wires down to the track.
2) Tape wires into a cluster.
3) Spiral wrap / cable wrap may not fit but would help.
4) I would avoid woven wrap, because it does not trap the wires.
Edit..your post said "channel", I'll read closer next time.
Picture of spiral wrap.
http://cableorganizer.com/spiral-wrap/