As with all things that are a few years old, I had a little back focus issue with the 645 Pro. These cameras have a screw attached to a mirror stop which you can fine tune the focusing when looking through the view finder.
During this little adjustment it appears with my almight strength i broke the mirror stop, This is a small 12mm L shaped piece where the mirror sits, which is used to reflect the image back through the view finder to help you focus on the subject.
Many days researching i had seen that this appears to be the most breakable part for these cameras, unfortunately Mamiya discontinued the part in question.
Lucky for me in this day and age we have 3d printing available, I glued the part back together and took it in to have it redesigned and printed, Here are the results below.