I own an old hp color Laserjet 4550 that's been giving me the "drum life low" warning for ages. This morning it finally changed to "drum life out" and stopped printing in the middle of a very important (and long) print job. Once it's out, there's no way to continue even if the print quality is fine.
After finding nothing on Google about resetting the drum counter, I decided to dig into the drum. The drum keeps track of the pages on a
93C46 serial EEPROM mounted behind the 8 pin connector on the left side of the drum. I got to this EEPROM and lifted the clock pin (pin 2) and reinstalled it. I was pleasantly surprised to find that the printer calibrated and finished printing my document fine. It now displays "drum error, replace kit", but it still prints. I guess it's set to continue printing if the EEPROM fails.I don't know how long this will work for, but it's working great so far. This will probably work for similar hp printers like the CLJ
4500.