I just setup an old HP DeskJet 660C on a pure Linux system (no dual boot). How do I clean the nozzles, so the print quality is better?

The best I found was a program called PUP which doesn't support this model. It hasn't been updated since 2000.

I found this page here about manual cleaning, but it's rather involved:
http://homepage.ntlworld.com/wilf.james/cartclen.htm

Thanks.