printing to Docutek issue ... rasters looking 300dpi (pixelly)

[Sean]

Hi,
 
 Printing to a Xerox Docutek from a PDF (version 1.4 compatibility created created in Acrobat 7) from FrameMaker 7, the screen captures look low-res, 300-dpi-ish (a bit pixelly).
 
 The Job options are set as follows:
 
 Resolution on the main tab = 600dots per inch
 
 On the Images tab:
 For Color and Grayscale Images Downsampling is turned Off and Compression is set to ZIP.
 For Monochrome Images (which I assume does not apply to screen captures), Downsampling is set to 1200 ppi for images above 1800 and Compression is CCITT Group 4, with Anti-alias to gray turned Off.
 
 The images in the FM chapters are generally set to a resolution to fit the text column, between 120 and 216 dpi with very few, if any, above that.
 
 These PDFs print fine off a variety of office laser printers (Kyocera and HP) and ink jets (mixed brands), etc. The Docutek in question prints text and line art fine and has a printing resolution of 600dpi.
 
 Anyone offer any advice?
 
 Thanks,
 
 Sean