You can only mess this up in three ways:
- Scratching the lens
- Leaving a fingerprint on the lens surface (hold by the edge).
- Not screwing things back in properly.
Avoid those three things and you're good, I promise. It's not hard, a 9 year old could do this.
To clean the lens:
- Unscrew the laser head/nozzle. It's pretty easy to figure out.
- The lens is held in place by an internal threaded "tube" (insert better word here) that can be removed by unscrewing with a key. It's almost like a standard slotted screw head, except hollow in the middle. The key is the exact width of the hole so it'll touch the sides of the slotted, threaded tube. (This sounds incomprehensible, but if you just look inside it's obvious how it works).
- Unscrew the lens onto a lint free cloth (microfiber towels).
- There's a silicone gasket too, don't lose that.
- Clean the lens with acetone.
- Put back in, curved side up. I forget which side the gasket goes on. Maybe there's two gaskets?
- Screw the threaded slotted tube back in.
- Screw back in the laser nozzle.