the pinion is sorta a pain since there easy to mess up when you try and take off the motors shaft, ive used crude methods that work ok for this, i used some wire cutters that i could close around the bottom of the pinion between the motor housing and gear, sometimes doing that you can just pull up on the plers and they pop righ off-make sure the cutting edge of the pliers is as close to the shaft as possible to keep from knicking the teeth-
maybee the white piece is worn out or cracked, i think its 2 piecesthat slide together, maybee try swapping another onto it i think its just 1 screw holds it on