The solution seems to be:
1. Take it back. The carriers have been very busy exchanging early Tours for more recent ones that seem to have fixed this trackball issue.
2. Replace the trackball with one from a parts supplier like
Cellular Nationwide Network - 3G, Sony, Panasonic, LG, SonyEricsson, Nokia, Tools, BlackBerry,
I did this and mine now works perfectly. Plus I'm sporting a spiffy looking
orange trackball.