The worst thing just happened to me! My best friend borrowed my sigma 28-300, he didnt secure it well on e tripod and wham! it hit e grown and now e bottom part of the lens(lock, af/m switch area) is cracked badly, until e AF/M focus button dropped out. what should i do?? e lens is still okay, only e casing and the switch is damaged. where can i fix it? or should i just get a new lens. =(