I had trouble with my RRB as well. I had to learn how to load the paper and now have no trouble at all.
Run your finger along the two guides that position the paper to ensure that the paper is held under them properly, then make sure that you use the top left corner of the paper to push it into the corect position. Don't touch the paper again and close the frame.
It works for me very time so I hope it can help you a little, before I adopted this routine I often had crooked prints too.