Pitney Bowes DM125 Operator's Manual page 55

Maintenance
9. Remove the protective tape or the black cap from the bottom of the new print head.
10. Squeeze the two gray tabs on either side of the new print head and slightly angle the print head
while pushing the print head flush against the wall.
11. Replace the ink cartridge, see
Pitney Bowes Operator Guide
OR
Replacing the Ink Tank Cartridge
February, 2017
if you need assistence.
Page 55 of 226