IBM Personal Computer AT Manual To Operations page 365

Note: See the "Ribbon-Color Knob
Adjustment" procedure in Section 1 of this
manual.
7
Perform the ribbon adjustment procedure. Then
press Enter (+--i ) to print the test pattern and
verify the adjustment.
Warning: Wait until your printer stops
printing before making any adjustments.
8
Return to Step 6.
Note:
If
you are unable to adjust the ribbon,
have your printer serviced.
9
Press Enter (+--i ) and refer to the screen for the
next test.
Test 2900-7