My replacement head laser was fine, but the original head laser was in there really snug. I pulled and pulled, and what finally gave wasn't the laser itself, but the yellow housing it comes in. It has a flared base that should have been big enough to keep it from popping out. I was terrified things were glued together underneath it, so I spent an embarrassing amount of time trying to shove the housing back in from above, even though it didn't fit (yet it got out somehow...?). Don't do this, it will make marks (which are fortunately very hard to see once the housing is in, but still...). Eventually I gave up and realized that the 'face' was held on by a simple ball joint, the 'head' and 'cowl' assembly was also held on by a simple ball joint, and the grey part behind/above the face in the cowl is held on by a single screw. Pop that out, pop the yellow laser base back in, then reverse the disassembly steps, and you're good to go.