Hi David.
Just a note to say that your solution to our 57.2 error was found just in time to avoid this old workhorse from ending up in the tip.
Our fault was actually the red wire to the fan had actually corroded through. I cut the othe two wires off, and resolded all back to the small board on the fan..
Thanks again for identifing the solution and saving our poor school from forking out quite a few hundred dollars for a replacement, which would not have been an HP brand anyway.