Digital BW, The Print

Has anyone experienced "random" changes in print density? I am printing with
an Epson 7000, MIS-FS, ImagePrint, and Photo-Rag (MediaStreet version.) I
have areas that contain solid fills and occasionally the fill (64% Black)
prints lighter. Nozzle checks are OK and I cannot find a difference in files
(in Photoshop the dropper says 64% and the Gray space is the same.)

Wendel