A couple of weeks ago, the reflex mirror in my Canon 5D became 'unstuck' from the mechanism that lifts it up during exposure. Fortunately, the mirror didn't fall out and break. I took my camera to the Canon service center here in Busan, Korea, to have them repair the problem. Their only option for repair was to replace the entire mirror box mechanism for approximately US$500. Given that I would need to pay $500 to replace the entire mechanism anyway, I figured nothing would be lost by trying to repair the problem myself. So, I bought some cyanoacrylate ("SuperGlue"), put a few small drops on the mounting points for the mirror, carefully put the mirror back in place, and waited a few hours for it to dry. The result: the camera is back to functioning as well as it was before the problem. Focusing accuracy doesn't appear to have suffered. Cost of repair: less than $3, and about ten minutes of effort.