IBM Personal Computer AT Manual To Operations page 368

5
Perform the printer self-test:
1. Press and hold the Line Feed button while
you turn your printer's power on.
2. When the test starts, release the Line Feed
button.
Note:
The printer self-test will take
approximately 10 minutes.
3. To stop your printer self-test before it
finishes, turn your printer's power off.
8000-2 Test