Apple Macintosh PowerBook 150 - Manual (Page 115)

A window has disappeared.
m Another open window on the desktop may have covered the one you’re
looking for. Move, resize, close, or hide windows you aren’t using until you
see the one you want.
m Windows belonging to open but inactive programs may be hidden. Choose
Show All from the Application menu to show hidden windows, and choose
the correct application program from the Application menu for the window
you want to view.
An icon is blinking in the menu bar.
m A program needs attention. For example, you may have set the Alarm
Clock to go off at a particular time, or PrintMonitor may be alerting you
to a printing problem. Make the program active by choosing the icon
for the application program in the Application menu, and take the
necessary action.
The trackball
The trackball doesn’t work smoothly; it sticks or jumps when rolled.
m There may be dust or dirt inside the trackball mechanism. To clean the
trackball, follow these steps:
1. Remove the trackball by turning the trackball retainer ring
counterclockwise and lifting the trackball out of its cavity.
You may need to use a pen or your fingernail to lift the trackball out.
2. Locate the small rubber rollers at the left and bottom sides of the
trackball cavity.
The rollers look like small rings or wheels.
3. Use any reasonably clean, blunt object (such as your fingernail) to
scrape any residue from the rollers. Do not use any liquid inside the
computer.
4. Replace the trackball and its retainer ring.
You just cleaned the trackball, and it feels worse than before.
m This problem is related to the way the trackball is lubricated. After you use
it for a few minutes, the problem should go away.
107 Tips and Troubleshooting