Infinity focus issue on 6x9 Folding Camera (Adox Sport) - why does this happen?

Dan Daniel said:

The packaging plastic used for batteries and such things- the clear parts- can make a nice shim material. Steve906's idea of making three sections, not a full circle, is good. You'll need to make the sections stick- glue or tape- for assembly.Bottle caps of assorted sizes are worth trying as templates for cutting- vitamin bottles or such might be the right diameters. Oh, the retaining ring!

The notches in the lens board are... well, I am not certain why there are two. Haven't seen that before. But one is for a pin on the back of the shutter to go into and stop the shutter block from rotating. Most likely the pin was removed by the previous owner and lost/forgotten. I see a hole in the back of your shutter that might be for a pin, but it looks as if it is 180 degrees off from the orientation on the lens board.

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