Again, many years later, I had the same problem with a Sears KS-2 that I bought for $10. I put new batteries in the camera and the shutter fired 3 or 4 times, then the mirror locked up. I followed these instructions and now the camera works perfectly! Probably the easiest fix ever. This is a really fantastic camera, with a wide range of shutter speeds, exposure lock, multiple exposure button, metal shutter curtains, etc. Well worth the minor trouble to get it working!