There are three ways of fixing the mini trackball of your key cluster module.

Cleaning the mini trackball

The cheapest (free) but the hardest way is to disassemble and clean the mini trackball. You can access the mini trackball using the guide below. It's possible to remove the top metal part that keeps the ball and spindles in place, and then you can remove the dirt from the spindles. Putting the metal part back can be hard or impossible, especially if you deformed it during disassembly. Fortunately, the following solutions should work.

Replace the mini trackball

This is a cheap and relatively easy method. The mini trackball is a BlackBerry trackball that you can purchase from numerous merchants. It is super-glued to the circuit board and can be removed with a prying tool. (The mini trackball is not electrically connected to the circuit board because it uses magnets.) Then, you can glue the new BlackBerry trackball in place of the old one.

If you haven't succeeded with the above, the following method should always work.

Replacing the mini trackball subassembly

This guide shows you how to replace the mini trackball subassembly of your key cluster module. Let's get started!

Unscrew the screw at the center of the back of the module:

Remove the case buttons:

Remove the keycaps with a keycap puller, possibly a DIY keycap puller, or bare hands:

Remove the top part of the plastic case:

Unscrew the three screws that hold the metal plate in place:

Lift the metal plate:

Lift the trackball subassembly:

Lift the inner subassembly out of the bottom case, disconnect the trackball subassembly from the inner subassembly, and connect the replacement trackball subassembly:

Put the inner subassembly back to the bottom case, put back the metal plate and the switches, then firmly push the trackball subassembly down to the three bosses that hold it:

Screw the plate to the bottom case with the three screws:

Put back the top case and the case buttons, and screw the screw at the center of the back of the module:

Finally, put back the keycaps, and you're done!