Now for the question :-
Does anyone know what adjustments these things require?
There is a screw opposite the actuation lever - what does it do?
I'm trying to avoid fiddling until I have a better idea of what I'm fiddling with.
On one web-site I have looked at - the writer expects to be able to lock the rear wheel using the drum break with the stoker seat empty. Mine can't, so I assume I have room for improvement.