[aiharkness]

It is a complete module, plus the decorative ring.

Do a search for 8900 trackball replacement. Likely you'll find several demonstration videos on youtube.

Also shop around for the trackball replacement. Buy a genuine RIM/BlackBerry part. Pay attention to what comes in the package. I think when I did it on an 8820 I bought the trackball module, a replacement ring, and the plastic tool to pop off the ring for 10+ USD.

No need to clean anything. Look at the directions you find when you search....I expect there is the retaining ring to pop off, and then the module will just drop out....that's the way it is on the 8820. The new module has to go in with the same orientation as the module you take out. Again, pay attention to the directions you find when you search. Don't go poking around inside. Just drop out the old module and drop in the new.