Bayer HealthCare RapidPoint 400 Series Service Manual page 319

b. Insert the long flat-blade screwdriver between the cartridge and
the side of the system and lift the tab to release the cartridge.
If the cartridge does not release from the system, push the cartridge
NOTE:
into the system to fully engage the anchors on the cartridge and lift the tab
again.
c. Pull the cartridge from the system.
Rev. C Replacing Components 319