I've never worked on a Chinon lens before so take this with a grain of salt.
The optics section is separated from the focusing body housing, screwing it back on you'll have to re-calibrate for infinity focus, which mean it'll depend where it threads on from.
Within the focusing body, there may be some type of thin bracket that will hold the lens in place to prevent it from threading out, some don't have this.
Once you have them connected, the front circle just threads on and the rear mount screws on. Just have to align it. Best of luck.
I can't get it back together :(
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