Thanks for all the pointers. I'll keep them in mind, but USB is just not going to be an option. I absolutely need parallel port printers because I'm using LinkSys Pocket Print Servers on my Novell network.
And just to follow up on my own post, it's looking like it might be the actual cartridge. I stuck an empty black one I had laying around in the printer and it stopped whacking out. Hopefully, if I just replace it, everything will be ok.
Fingers crossed...