My Crown Graphic has a P31 cam (for 132mm), but a 135mm Xenar: I'm looking for a P6 cam. Who can help?

PS: I live in Paris (France, not Texas ).

Do not assume the cam is incorrect; test the GG image / RF for agreement before replacing the cam. The marked FL of the lens is nominal, and a lens marked 135mm is virtually never actually that length. The factory would optically measure the actual FL, and fit the appropriate cam.

So take the camera, on a tripod, to some place where you can achieve infinity with confidence. My favorite is a TV antenna that is about a mile away. Carefully focus with the RF, and then lock the yoke to keep the focus position from shifting. Open the lens and check the GG image with a magnifier. If the GG/RF agree then the infinity setting is good (if they are off then the infinity stops for the lens may need to be adjusted before proceeding futher). Find several closer objects that will be easy to focus on, at about 100', 50', 25', 10' and 6' and repeat the test of the RF/GG image. If the RF/GG images agree over a range of distances, you have the correct cam. The key to the procedure is starting with agreement at infinity.

Thanks a lot! I'll try