Quote Originally Posted by David Lyga View Post
Countless lenses have been taken apart by me.
Me too... and some of them have gone back together again!

No manufacturer of a mass produced item would design it so that every part needed expertly applied precise adjustments. A good design is one where you can put all the pieces in a box, shake it and have a finished part fall out (an analogy a QA manager I used to work with would use). Not literally, but I'm sure you know what I mean.