does anyone have any experience with replacing the viewfinder glass in a plaubel makina 6x7 folder? attached is a picture of the problem - would this be a difficult or expensive repair? tough to find a replacement
You could perhaps try making a replacement from a microscope slide, a box of them only costs a couple of pounds (Ebay), you'd have plenty to go at. Make a rigid template from plastic etc. and scribe around it with a diamond tipped scriber.
I suppose it's possible that the original glass could be coated, but if you make your own contrast can be improved by painting the edges black. You can also get optical quality Perspex sheet which may be easier to work but it can be expensive.
Looking at my Makina 67 I find also this plane glass window, but I also see a lens directly behind this plane glass.
I made an image with my mobile phone - it needed some setup (my desk lamp plus a torch) to make it visible, but I think now it can be observed in the image attached:
I am not quite sure if this lens is visible in your image (but as I found it depends on the light if one can see it in a photo).
Edit: Looking more in detail at your image it also seems that the cover metal sheet is bent (on the backside of the camera at the position where it contacts the cold shoe) - if this is the case it may be a more serious defect than only the viewfinder glass.