I know one of mine was very loose as well. I do not have the trailer any longer to check but I seem to recall there was a screw on the side of the latch that I had to tighten up and I may have actually changed the screw out to something larger to keep it snug.
You could also give Hehr a call they should be able to help you. Might want to call Scamp
first and ask what the model number on the windows
used was first - Hahr make a LOT of different windows.