I just spent an hour sorting out the sail.
I tried the Powerex extension 1st and I couldn't get enough downhaul. It felt like the the ratchet ( or me ) was going to break. It wouldn't even think about rotating.
I then tried the severne RDM ext. I managed to get extra downhaul on and it rotated well although maybe slightly overdownhauled.
I figured out a way to thread it.
Thread clockwise. Starting bottom RHS where it comes out go to the top RHS then down to bottom LHS, up to top LHS then down through the middle bottom , over the middle top and cleat off.

Well I should now have a usable sail next time it blows..
