Most "v12 Fixes" play a big role in damaging the DVD diode on the optic (lens) unit. Any fix 
that limits voltage or changes the impendance on the Focus or Tracing coils (diode, etc) causes 
the gain on the DVD diode to go higher in order to spot (read) a disk properly. When the gain goes to 
high it will blow the DVD diode.

Example:
Focus and Tracking coil = Magnifying glass
Sun Beam = DVD diode (laser beam)

A lens in principal works almost the same as a magnifying glass with a sun beam passing thru it. 
Let us say you want to burn a piece of paper with a magnifying glass and a sun beam, you would 
simply move the magnifying glass closer or further away from the paper to get the most concentrated 
part of the beam on the surface of the paper. Now limit the distance that the magnifying glass can 
be moved closer or futher away from the piece of paper. What would happen now is that you will not 
allways be able to get the most concentrated part of the beam on the surface of the paper, thus not 
allowing you to burn the paper as efficiently as without the limitations of movement to and from the 
paper. Once the movement is limited, the only way to burn the paper more efficiently would be to 
strengthen the sun beam that is being shun thru the magnifying glass. 

What this means; 
When a limitation is placed on the focus and tracking coil, the gain on the DVD diode has to increase 
to accomidate the lack of performance from the coils. Thus increasing the chanses of the DVD 
diode popping.