Try checking the flexy-ribbon cable running from main to optic assembly board.
Occurred to me once where new optic wouldn't operate, and it turned out (after thorough
testing) one channel amongst six of what appeared to be still perfectly fine cable was bad.
After flexy-cable replaced, everything was good.
*Suspect also other connections that are possibly susceptible/get in the way/affected over
long haul when tray of disc travels in-out, or one that needed plug/unplugging when
technician is replacing the assy.
Occurred to me once where new optic wouldn't operate, and it turned out (after thorough
testing) one channel amongst six of what appeared to be still perfectly fine cable was bad.
After flexy-cable replaced, everything was good.
*Suspect also other connections that are possibly susceptible/get in the way/affected over
long haul when tray of disc travels in-out, or one that needed plug/unplugging when
technician is replacing the assy.