Datamax-O'Neil E-Class Mark III Printhead Bracket and Screw Upgrade - Manual (Page 5)

4.) Gently push tabs inward to drop the printhead cover (Fig 4)
Do NOT change the media sensor position
Figure 4
5.) Remove the printhead screw (Fig 5)
Figure 5
3.) Using needle nose pliers, hold the side of the e-clip in place.
Then, using a small flathead screwdriver, gently pry the e-clip outward to remove it (Fig 3)
Figure 3
The printhead screw will not be re-used.