I took about half an hour today cleaning my old Blackberry trackball which was refusing to scroll upwards easily. This is the amount of dust that collected inside the trackball assembly of my old Blackberry 9000 over three years worth of daily usage. No wonder why the trackball was so reluctant to move!
This is probably one of the reasons why RIM decided to go with trackpads on newer Blackberry models: no small moving parts collecting dust.
Thanks to a YouTube video for helping me disassemble and reassemble the phone.