There is an ebay seller or two that will cut to size if they do not stock the proper size ground glass for your camera.
Your camera can use standard ground glass, it does not require anything special.
If you have a ground glass in the camera measure it, if you do not have aground glass in the camera measure the ground glass opening.
If you have a ground glass and it is dim remove it from the camera and wash it in warm water and dish detergent, and do a final rinse in a weak Photo Flo solution then air dry or dry with a lint free towel.
Handle the ground glass by the edges only and rub it with your fingertips only when washing. A fresnel can be washed the same way making sure to rub with the ribs not across them.
I washed as you suggested & it made a great improvement! Thanks!