Well I dropped my 10-22 off at Canon Irvine... She's is spending the next 5-10 business days alone ;(
Shooting a wedding on Sat, I zoomed out to 10m and heard a CRUNCH.. thought in the back of my mind that it was VERY strange, but turned the ring a few more times and it seemed ok. Then the fun part.... I went to "un-mount" the lens from the body and it would not release!!! After turning and wiggling it i finally got it off, and it seemed that the plastic part on the base of the lens and been pushed out of the lens body,
I tried to gently push the plastic back but it would not go in. The only thing i could do was completely remove it. That is when a small plastic part fell out (I am pretty sure it was a tab that locks the cover in place). I finally got the cover back on and it seemed ok, but I did not shoot it anymore, in fear that the element might had been knocked out of alignment.
So yesterday I dropped it off, hoping it will be taken care of 



