The screw is the latch adjuster and should be set to allow the hinge to
swing only enough to open fully for the space around the window. If you've
tightened it to far in, then you've essentially locked the window. I'd
advise you either contact the builder or Velux to get the best answer on
what to do next. Contacting the builder and telling him that the window has
jammed may get the job done of putting it right for free.
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