If you have a blackberry pearl and you work near metal dust or filings it will not last long.
I took mine to SRL yesterday and needed to use it with dirty hands. I wiped them off on my shirt, really, then used it a few times and noticed that the trackball had stopped running smoothly. The problem is not just the dirt (see the black streaks around the knurls on the little potato masher shafts), but metal flakes that stick to the magnets.
Turns out the blackberry’s trackball works with four little hall effect sensors on the mother board (you can see one of the black sensors in the top right of the cavity where the trackball was). The black ends of the four little (TINY) potato mashers are magnets and attracts dirt… and tools.. and make them endo and stick to things in very annoying ways as you try to reassemble the trackball. If you get a metal flake wedged between the sensor and the magnet cylinder as you roll the cylinder past it you draw nice metal residue rings around the black magnet, which do not come off easily (but fortunately do not affect operation).
Cleaning each bit carefully with rubbing alcohol, blowing out the cavity and the magnets, and particularly working on a strip of tacky paper (like painter’s masking tape) makes it possible to clean the parts and get the little metal bits off. The pearl itself is very likely to make a break for it across any gradient. It’s only 3.5mm in diameter; do not lose it.
These instructions helped. Basically pry the silver ring off gently from the front (under the 2/t/y key) and pop the trackball assembly out. Mine did not have the second metal retaining ring in it and seems to work fine without it.
All back together now, but it will not be accompanying me into environments with metal dust and chips as the sensor is perfectly designed to draw them into the workings and specifically right to where they will jam the rollers. It does seem fairly immune to finger grease and pocket lint though.