Hello. I have just bought a FM2 with the DK3 eyecup. However, when I tried to screw it in the rubber that surrounds the viewfinder peeled off. When I searched on the web I have found out that I needed a replacement eyepiece finder. Now that the eyepiece rubber fell off, and there are no threads anymore, do I need to get it fixed, or will the eyepiece finder fit without the threads? Thanks.