The display reports that time and date are not set.

"Time and Date Not Set" message

Cause: The clock chip has stopped, which nearly always means flat AA cells or a poor battery contact.

Checks

• Check battery voltage and the holder contacts.

Fix

• Replace the batteries, then set the time and date in the utilities menu.

Systems

• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• "Country code must be specified" message
• Schematics may show W1/W2 as a display-type setting
• G10 error with serial number all zeros
• CPU board completely dead
• Game clock runs at a fraction of real time with new batteries
• Settings are lost at power-off even with fresh batteries: bad battery diode D2
• 'Check F114 and F115' then ground short row 1: failed 12 V regulator on CPU
• Outhole, shooter diverter and gumball motor all dead: CPU board chip at U4

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part One, Clay Harrell (pinrepair.com)