I follow the regimen of:
1) Turn my Bold off.
2) Take an alcohol prep pad (I'm diabetic and have to inject Insulin) and just roll the prep pad over the trackball, which is still in my Bold, for about 45 to 60 seconds.
3) Let it dry out for about a minute and then
4) Switch my Bold back on and enjoy it
I do this every second or third week and have had no problems with a sticking trackball.
Good luck!