printing too light with a DEC LN17ps

[ACRO]

I'm running in Mandrake distribution 10.0 with kernel 2.4. Sometimes I run also in Windows 2000 Pro.

I have a HP OfficeJetPro1150C which works just fine with both Win and Linux. However I have acquired and old DEC LN17ps laser printer which I would like to use as default (cheaper ink)

This prints just fine with Windows, but prints too light with Linux. I've opened various administration tools, for instance the CUPS administration tool, which calls my LN17 printer "DEC LN17 Foomatic/hpijs (recommended)". Under "Manage Printers", there are possibilities for adjusting print quality, but this seems to make no diofference. Also I have tried changing text and image "brightness" in the KDE printing manager, but this seems to make no difference either. There are some files called "DigitalLN17.ppd" which have been installed in different places. I have looked at these with an editor, but cannot see anything obvious to try changing.

Can anyone suggest anything?
Thanx