A little update. I found the threading diagrams not easy to follow. There are two Youtube videos I found helpful. One by Lacey in the FB group and Nutts have a demo. I immediately found my mistakes from these. However I don't think I have mastered the mysterious above needle plate - there seems to be a twist to do but it is all obscured. Maybe this is typical of some of the new generation of coverlock machines.
The needle threader works well but it appears a bit stiff at the moment, requires a big press to get it to descend. Looks as if it is working well. Chains on and off. I'm not yet certain how you clear the stitch fingers if you want to.
My largest knit double fold binder fits on the outer holes. The position is quite snug and close to the foot edge but there is enough room to train strips under the foot with tweezers. However I wouldn't say I have got it in the correct position yet or which needle position is easiest to use it with on narrow coverstitch.