One of my friends in NYC is a chief technologist in camera repair filed, most my knowledge came from him and helped by him. I provided this DIY for these who fell capable to DIY, your mileage maybe different but at least you have some information about how it was done. I did mine under my friend help, not really difficult but you have to take caution not to tear the ribbon from the light meter. I just share my experience and I am not response for any damages to you or your camera or anything esle due to this post. Standard disclaims apply. Tools and part: For M6/M6TTL: you need the ring wrench from micro-tool, one for the one around the shutter release button and another for the flash PC. Spanner. MP/M7 style mirror and plastic filed lens (about $20, $10 plus some processing fee and SH fee) 1. Take off the top plate by remove the collar around the shutter release button and film advance crank . The flash PC, the film rewind cranks locked by a setscrew, remove the setscrew and remove the film rewind crank. 2. Mark the bright mask frame position by draw line around the two screws fix it, if you can get around, you do not need to remove the mask frame. There are two screws hold the mirror and the mask frame as well as ribbon from the meter. There are two LEDs at the end of ribbon, also a plastic magnifier cover the tiny LEDs; it can fall off due to old age. 3. Remove the two screws hold the meter ribbon, mirror and mask frame and replace with the new mirror (the bottom has a dent). 4. The difficult part to glue the plastic filed lens in to the mask frame, it fill in right the cut off portion at the bottom is for the LEDs, you need very little clear glue to glue it on to the frame at the top and bottom, if you put too much you will ruin the movable bright line, it will glue them together. 5. Test the movable bright frame makes sure they are functioning. Then put back the top plate. Not that difficult to do it. I did mine on my M6 and has been working great. I would say the update M6 is better than my M4. I will post some pictures late on.