I have good experience with the lockjaw folders, one has to be a little carefull not to squeeze the locking bolt unless the bike is straight.... although its diffifcult even to screw that up . than tighten the bolts and you should be fine ....
there are many ways to skin a cat ... therefore you get many ways from actual owners to close the hinge ... all of them are ok... over at Dahon formum there are folks like Trail X who works for Dahon ansd I think he said a few things about the hinge ...
http://files.dahon.com/support/manua...fold_guide.pdf
in more detail here
http://files.dahon.com/support/manua..._manual_en.pdf
page 22 to 25
all the best Thor