As you have seen, they do not design CD drives to be opened and repaired.
I usually need to:
Remove the face-plate on the door.
Remove the bottom and top housing.
Sometimes, you have to manually remove the entire tray assembly.
CAUTION: Many trays require specific alignment to the internal gears for the drive to function.
Watch EVERYTHING very carefully.
Causes for the motor to not spin:
Dirty laser - no disk detected.
Tray does not close all the way, and motor switch is disabled.
Bad motor switch.
Bad tray gears.
Bad spindle motor.
Of course, if you have a bad part, good luck finding replacement parts.
Most of the parts inside a CD drive are semi-custom OEM parts.
I just picked up a refurbished 8X drive for under $30.
The Computer Geeks, www.compgeeks.com
have a 40X drive for under $50.
Chas