3.9 Replacing the Gap and Black-mark Sensor Module 
 
1. Open the printer right side cover. 
2. Disengage printhead release lever. 
3. Refer to section 3.1 and 3.4 to remove electronics cover and multi-interface board. 
4. Disconnect the gap and black-mark sensor connectors from the main board. 
 
5. Remove 5 screws to take off the lower printhead mechanism.