After playing with the game console last night (and falling asleep,
lol), I noticed a trend... It's grinding gears isn't so intermittent
as I thought.

Batman and Robbin: When going from the title screen to the Options
menu, it grinds gears. Also when going from Options to Title Screen,
it also grinds gears.
Sonic CD: In Time Trial screen, selecting a level grinds gears as
soon as it starts to load a level.

Oddly, all three times it grinds gears on "command", was when it was
playing a CD audio redbook track, and went to reading data (on track
"1")..

This is leading me to confusion, because home switch is fine, i tested
it, resoldered it, cleaned it, and it seems that it's the action of
throwing the laser closer to the spindle... (the start of the
movement, not the "stopping")..

Well, I guess it's just when the thing needs to move the sled somewhere else
in a hurry. The play in the gears allows them to slip momentarily as the
motor tries to accelerate the optical block. I wouldn't say that it is any
kind of real 'mystery' to lose sleep over. Just find some replacement gears,
or tilt the motor, and I'm sure it will be fine.

Arfa