Me and my brother just installed a new HOP-M3 to our recently acquired Duo-R that was showing signs of a worn-out lens and after replacement we're just not getting it to read discs.
From what I understand, though, it looks like the intensity adjuster is the plus-shaped white knob at the very right-bottom corner of the HOP-M3. We've experimented it with a little but so far nothing to mention.
Just like you, I would like to get a confirmation of how this is done.
EDIT:
We've fallen back to the old HOP-M3 due to the apparent calibration issues with the new one - the new one does attempt to read CDs just fine and all of the mechanics work (we tried without a CD too) - so for now we'll be using the old lens until we find more information about the intensity adjustment.