IBM Personal Computer AT Manual To Operations page 122

10
Press down on the cartridge and slide it to the
left until you hear a click. The cartridge is now
locked in place.
11
Be sure the ribbon is not folded in the stuffing
wheels (pull the ribbon slightly if necessary).
Then press down on the locking pin to release
the yoke assembly.
Ribbon
Locking Pin
1-12 Color Printer