Please bear with me as this is complicated and difficult to explain clearly.
The film plane does not agree with the ground glass on my C-33. When focused at 10 feet with the 80mm, the picture comes out focused at around 8 feet. The repair guy says the lens mounting bracket is bent so that the taking lens is just slightly farther from the film than the viewing lens is from the ground glass. He points to it not being exactly parallel with the main body when cranked all the way in. The difference from top to bottom of the mount is about 1 mm. However, when visiting Central Camera in Chicago I saw this exact difference on the other Mamiyas on their shelf. The sales guy said it was more likely that the lens assembly was out of line and suggested that I do a test with the other lenses.
So I marked the front of my house with tape at 6" intervals, set the tripod up at distances of 5, 10 and 15 feet at 45 degrees from the wall, and took one shot at each distance with the 80mm, 105mm, 135mm and 180mm with the apertures at maximum opening. All shots showed the plane of focus to be some distance in front of the intended focus point. In each photo, the in-focus area is a small strip going straight from top to bottom.
If the mounting bracket were indeed out of true then both lenses would point slightly upward, and wouldn't that be the same as a slight backward tilt in the front standard of a view camera? If so, I would expect the area of focus to move diagonally on the negatives, rather than straight up and down, due to the wall being at a 45 degree angle.
Might I be lucky and only need the ground glass position to be adjusted with slightly thicker shims?