Gee Whiz, another printer problem
Most such problems are solved by selecting the paper type but perhaps more important, to select Best Photo on the first page of the Properties.
For example, if I print a purge file (strips down of each colour as a jpeg file) I get some black bits in the Yellow - they totally disappear if Best Photo is selected - whether the actual paper used is Plain or whatever. No .... I have no idea why - just that it solves that problem.
Zone8: Although I am a handsome geniearse, when I stand in front of a mirror, I vaguely recognise the ugly idjit standing on the other side!
LINK: For B+W with Epson 1400 (and other models) using black ink only PLUS other useful tips:
Cleaning DSLR Sensors, including Kodak DSLR Factory Cleaning method:
Solving back/front focus problems on Sigma DSLRs