You might try a google search for "HP error codes". Several of the hits will be from companies supplying replacement assemblies and they supply disassembly instructions with their parts. You may be able to get a copy of their instructions from them.
Ed Fair
unixstuff@juno.com
Any advice I give is my best judgement based on my interpretation of the facts you supply. Help increase my knowledge by providing some feedback, good or bad, on any advice I have given.