Here are 3 cases reported to www.saferproducts.gov:
Look at the small amount of material in the actual hinge; if the latch is a bit loose, that transmits all the force exerted on the handlebars while riding, to the frame! With the latch not tightened properly, it snaps easily.
There are numerous cases that were also reported at the now-defunct Dahon forums. Here's one:
Fascinating reading. Note that Josh Hon himself actually advocated superglue for the Delrin block adjustment!! "Sorry boys, we stuffed up the positive retention of the Delrin block screw but superglue will see you right." That never should have happened.
This incomplete list actually very neatly highlights my exact objection against that hinge design - there is a HUGE scope for things to go wrong. The design is not bulletproof, far from it. And worst of all, the screws are not retained positively. For example, those screws you mention that hold the sliding latch plate - they should have been shoulder screws. This is just one item in a list of things that a competent engineer would have done differently.Most of the "problems" with stems come from overzealous adjustment freaks, who cannot leave good alone and have the urge to optimize beyond their abilities. I have seen delrin blocks explode, due to way overtightened adjustment bolts, they will also show excessive wear , if they are overtightened.... plus they will need more frequent adjustment as well.
I have seen tightened down guide bolts ( for the plate, who needs to move freely ) making a folding stem a more or less solid one, without been able to fold.... and if than the lips are rounded off...due to not opening jaws for lack of the better word ....
grinding away with every fold..... people who open the handle just half and force the stem to close ... and and and
No, I am utterly convinced the hinges are failing due to design issues, not over-zealous adjustments or material issues. Don't forget, Dahon had a HUGE loss in store if they didn't fight that conclusion tooth and nail. So money is at the bottom line, and as soon as money is at the bottom line, integrity goes out the window. You can't convince anyone who looks at the evidence with an open mind, that the design is not at fault here. "Ah yeah, mate, some hinges broke due to crappy workers. And yeah, others are breaking due to the owners adjusting the shiite out of the hinges! But it's not my fault mate!"