How to Upgrade, Repair, Disassemble a Hewlett-Packard (HP) Printer

Do you need to upgrade or repair your Hewlett-Packard - HP printer? Here is a collection of free take apart instructions, disassembly pictures, cleaning advice, upgrade and repair manuals, as well as do-it-yourself (DIY) tips and tricks for DeskJet, LaserJet, ScanJet, ThinkJet printers and for ink or toner cartridges. If you have written a guide yourself (or if you know of a maintenance tutorial not linked here), please submit a new entry.

Hewlett-Packard - HP Deskjet 670	Printer modding: putting a motherboard into the paper tray (in German).
Hewlett-Packard - HP DeskJet 970Cxi	This illustrated guide provides step-by-step take apart and cleaning instructions for an old inkjet printer.
Hewlett-Packard - HP DeskJet 2000C	Disassembly and repair of the ink pumping systems.
Hewlett-Packard - HP DeskJet 2500C	A pump station repair guide.
Hewlett-Packard - HP DeskJet 5550	Power Brick Mod Guide: convert the power brick to use a traditional plug-in cord.
Hewlett-Packard - HP Laserjet 4+/4M+/4P/4MP/4V/4MV/5/5N/5M/5MP/5P/5SI/6P/6MP	Do It Yourself Printer Memory: how to convert 16MB standard PS/2 Fast Page modules into SIMM modules.
Hewlett-Packard - HP LaserJet III	How to repair malfunction "50 SERVICE", by checking the fuser and soldering "pseudo" resistors on different PCBs.
Hewlett-Packard - HP LaserJet III	A complete step-by-step disassembly guide with pictures (in German).
Hewlett-Packard - HP LaserJet IIISi, 4(M), 4Si(MX), DJ 1200C(/PS), PJ XL300(/PS), DnJ A/B, DnJ 200/220 and DnJ 600	Printer Memory Explained (PS/2 SIMM). Expanding the memory of your LaserJet or DesignJet.
Hewlett-Packard - HP LaserJet 6P	Exit Roller Replacement Repair.
Hewlett-Packard - HP LaserJet 1100	How to replace the feed roller and the fuser.
Hewlett-Packard - HP LaserJet 1100	Troubleshoot chronic paper jams. Examine the pickup roller and the separation pad and spring.
Hewlett-Packard - HP LaserJet 2100, 2100m, 2100se, 2100n, 2100xi, 2100tn	Illustrated lid removal instructions, to replace the feed roller.
Hewlett-Packard - HP Network Scanjet 5	Hard disk replacement, power supply repair, pictures from the inside and conversion to FreeBSD.
Hewlett-Packard - HP ThinkJet	How to recell a dead printer battery pack is dead.

Manufacturer Information, Customer Service

Hardware Maintenance Manual, User Guide, Service Manual

As far as I know Hewlett-Packard - HP doesn't provide free service manuals.