I finally found the right torx tool (right angle thing I normally open hard disks with!)
Open hood about 70cm, undo velcro straps, Loosen the screw:
Which releases the elastic
and outside its very easy to sew on a replacement a similar length. Clip back over screw and tighten! Hood now closes without catching on the sides! Previous fix only lasted 6 months (staple elastic over old one – as seen on youtube)