Printer Tech Tips Below is a list of service mode for HP Laserjet:   HP Laserjet Pin Number 2300 11230002 2410* 10241004 2420* 10242004 2430* 10243004 P3005 10300506 P4014 05401408 P4015 05401508 P4515 05451508 M3027/M3035 11303506 M5025 11502506 M5035 11503506 4100MFP* 04410002 4104MFP* 04410002 4200* 11420002 4240* 04424005 4250* 09425004 4300* 11430002 4345MFP* 11434504 M4345MFP* 11434506 4350* 09435004 5200 05520006 9000* 00900001 9000MFP* 00900001 9040* 11904005 9040MFP* 11904005 9050* 11905004 9050MFP* 11905004 M9040 04904008 M9050 04905008 3000 11300005 3500 10350003 CP3505 06350507 3550 10355004 3600 11360005 3700 10370003 3800 11380005 CP4005*** 10400506 4600 04460002 4650/4610 054650004 4700*** 09470005 4730MFP*** 09473005 CM4730MFP*** 05473007 5500 04550002 5550 09555004 CM6040 04604008 CM6050MFP 06604008 9500 04950003 CP3525 09352508 CP4020 11402509 CP4525 11452509 Note: * While powering up, wait for memory to start. Hold check button until all 3 lights are solid. Down arrow to New Maintenance count and press check button ** MFP; while powering up, wait for memory to start. Press & hold the '6' button down until all 3 lights are solid. Use the '3' (up) and '9' (down) keys to find New Maintenance kit. Press '6' to execute *** Does not have consumable reset option. Consumables will reset after new unit is installed. *This Tech Tip is contributed by Laser Pros. Visit their website www.LaserPros.com or email any question to marketing@laserpros.com.