If you own a LaserWriter 12/640 PS or 12/640 PS Plus, Apple suggests the following:
1. Check to see if your printer has already been modified. There are two markings to look for:
If you have the original shipping box, check to see if there is a blue dot on or near the UPC code label. Or remove the paper tray from your printer and look for a white dot on the left side black plastic inside. (If your printer was manufactured after May 1, 1997 your printer has already been modified.)
2. If you cannot locate either of these markings, please contact an Apple Authorized Service Provider to schedule an appointment to have the modification performed at no cost to you. In addition to the above procedure, modifications to reduce the possibility of paper jams will also be performed.
If you need to open the top cover of your printer prior to your reseller visit for modification, Apple recommends that you turn off your printer before opening the top cover.
Customers in the United States may call the Apple REA Information line at 1-800-482-2775 for information on established Repair Extension programs.