Sharp FO-2550 Operation Manual page 200

Installing a Print Cartridge
7
Press the 3 key if you installed a new black cartridge, or the 4 key if
you installed a new colour cartridge.
(When installing a previously used cartridge, press the 1 key for an
old black cartridge or the 2 key for an old colour cartridge.)
NEW BLACK CART.
The cartridge will return to its home position. If you pressed 3 or 4
for a new cartridge, the Sharp MFP will print a test page for
printhead alignment.
8
If you installed a new print cartridge, look at the test page and locate
the line that comes closest to forming a perfectly straight line.
12-12
NEW COLOUR CART.
or
In this example, line 13
comes closest to
forming a straight line.