The optical drive "dead". If not a "mission impossible" I'll try to repair my loved iMac.
In the Mac community "i-fixit" is a "Vangel" for people as me, so I founded all I need (of course)
The optical drive was delivered with swiss precision (ordered 01/19/2012 from USA - delivered 01/24/2012 in Italy... wow)
Following the guide the "operation" goes very smooth
The only difficulty was on step 17: the left bracket ear was very hard to squeeze: I've done many attempts.