I stupidly cleaned the yellow tinted mirror on my Crown Graphic and the coating came off. Anyone know of replacements or mods that can be done. I tried yellow highliter but you need to put multiple coats and it starts to blur.

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I stupidly cleaned the yellow tinted mirror on my Crown Graphic and the coating came off. Anyone know of replacements or mods that can be done.

Not stupid. The coating on some beamsplitters comes off with window cleaner, some come off just rubbing the grime off with a cotton swab.

http://www.graflex.org/articles/romney/rangefinder-mirrors.html
Get new beamsplitter at http://www.scientificsonline.com/product/mirror-type-beamsplitter
cut it to size with a glass cutter, moderate difficulty. Clamp between two pieces of wood holding one side stationary while press down firmly on the other side.
the new material is thinner than the original. put paper shims along the mount frame between the frame and mirror to position the front surface at the same position as the original. Put the coated side forward.
recalibrate the rangefinder according to the service instructions
http://www.southbristolviews.com/pics/Graphic/manual-pdf/TRFService.pdf

Does it need to be yellow like the one that's in there? Is the one your link shows the one I should order? I just want to double check that it's the mirror on the right side as looking through it.

I took a quick look at the adjustments and it says I need a master cam. Where do you find one of those?

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Does it need to be yellow like the one that's in there?

No. don't know if yellow was the coating they used, added for contrast, or from age.
Some of the new stock is clear, some light blue. You can always add a thin filter material of any color over the mirror if you wish.

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Is the one your link shows the one I should order?

yes. link provided for clarity and convenience.

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I just want to double check that it's the mirror on the right side as looking through it.

beamsplitter on the right, standard mirror on the left as you look through the rangefinder.

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I took a quick look at the adjustments and it says I need a master cam. Where do you find one of those?

Make one. Use your existing cam for the outline and make the top the required height for the last half and the lead edge tapered for easy insertion. I use .030 brass plate available at hardware and home improvement stores. The originals are nickel plated aluminum. Aluminum or steel can be used also. Cam making was well discussed several years ago. use the search function for cams or rangefinder cams selecting the all the terms check dot. limit your search to speed graphic help to reduce erroneous results.

Thanks for all your help.