How to Repair a Broken Pinion on a QX3 Microscope

Remove the four Phillips screws on the baseplate that covers the stand. Remove the baseplate.

Open the rear storage compartment and tilt the door fully down and away until it clears the stand. Remove the door and set it aside.

Remove the two screws securing the base to the stand and separate the stand from the base.

Pry the trim cover off the blue focus knob on the right side, using a small flathead screwdriver. Remove the Phillips screw that holds the right focus knob to the focus shaft bearing. Pull the knob off the shaft bearing.

Remove the two long Phillips screws that secure the two sides of the stand together, just above the right focus knob.

Hold the two sides of the stand together. Crank the microscope stage down to its lowest position by rotating the left focus knob. Slide the stage and the pinion rack out of the stand. The stage will remain connected to the stand by two wires for the illumination lamp.

Separate the two halves of the stand. Unplug the wires for the illumination lamp at the push connector.

Pry the trim cover off the blue focus knob on the left side, using a small flat screwdriver. Remove the Phillips screw that holds the right focus knob to the focus shaft bearing. Pull the knob off the shaft bearing.

Compress the focus shaft bearing's brake shoe spring with your finger to release pressure on the shaft bearing.

Pull the focus shaft containing the pinion gear out of the stand.

Remove and replace the broken pinion gear on the shaft.

Reassemble the QX3 microscope.