Lexmark MX931
Turn off the printer.
Open door A.
Unlock the used fuser.
Remove the used fuser.
Unpack the new fuser.
Insert the new fuser.
Lock the new fuser.
Close the door.
Turn on the printer.
Avoid printing delays. Install a new imaging unit when the printer prompts you to replace it.
Change the transfer roller regularly to prevent toner leaks.