I just checked the back and all the screws seem be in tight. Nothing is rattling as far as I can tell. Fromt element and the lens tube seem to be on tight. When I shoot it with a Nikon D40, I don't see much issues at the edges like I have had on film.
However I did put on a very large lens hood and have also used a uv filter. Going to try without both and just a step up ring as a "hood". Seems like a long shot but will try it anyways.