I originally got 65mm lens with my RB67 and after roll or two of film it quit working. KeH sent me 90mm lens as a replacement. My question is caring for the new lens so it doesn't suffer the same fate (the old one would close but not reopen for the exposure.) Is it safe to leave it attached to the body when not in use? It doesn't seem to be an issue on any of my other cameras. I there something I could have possibly done that caused the lens to fail? It seemed to fail after one shot on my third role. I do have lens cap and a back lens cap if it's not on the body.