top of page

HP Printer Parts Technical Support Blog

Scroll down to view articles and results.

Help support Metrofuser so we can continue helping you.

Complete Installation Guide For The 4200-4300-4250-4350-4345 Fuser

Updated: Nov 15, 2019

Technical Service Bulletins

LaserJet 4200/4300/4250/4350/4345 Fuser

Hewlett Packard has identified a manufacturing flaw in some LaserJet

4200-4250-4300-4350-4345 printers which may cause a gear inside the rear

of the printer to fail prematurely, resulting in grinding noises, wrinkled pages

and/or paper jams.

If your printer exhibits any of these symptoms before or

after replacing the fuser assembly, try the following field adjustment:

Refer to the service manual where necessary.

1. Remove the Face-up Exit Tray.

2. Remove the Fuser Assembly.

3. If the Duplex Unit is installed, remove it from the printer. If it is not installed, slide

the Duplex Cover out from the rear of the printer.

4. Remove the Left Side Cover.

5. Remove the Formatter Cover.

6. Remove the Formatter Assembly.

7 Locate the seven M3 screws securing the Power Supply - there are four behind the

Formatter Assembly and three on the other side of the printer. Loosen all seven

screws but do not remove them.

8. While facing the rear of the printer, grab the Power Supply and pull it towards you

and downward. This will situate the screws in their lower-inside position.

9. Continue to hold the Power Supply in this position and retighten all six screws.

10. Replace the Formatter Assembly, Formatter Cover, Left Side Cover, Fuser Assembly

and Face-up Exit Tray.

11. Test the printer for at least fifty pages to ensure that the issue has been corrected.

12. If the printer continues to exhibit the original symptoms, the Swing Plate Assembly

(RM1-0043) is worn and must be replaced.


Helpful Resources

When replacing the fuser, it is highly recommended that the swing

plate assembly is very carefully inspected. If the swing plate gear that drives

the fuser is even slightly worn, we recommend it be replaced immediately. If

not, this can lead to premature failure of the newly installed fuser.

The various 4200 and 4300 series fusers look almost identical but are not

interchangeable. They can easily be misidentified, leading to problems upon

installation/replacement. The chart below shows the error code displayed in

each instance of the wrong fuser being installed any into of these printers.

In 4200 RM1-0013

50.5 FUSER ERROR Printer at power-up

50.5 FUSER ERROR at power-up

In 4250 Printer RM1-1082

13.20.00 JAM IN TOP COVER AREA at power-up

50.5 FUSER ERROR at power-up

In 4300 Printer RM1-0101


13.20.00 at power-up


Important Note: A 50.5 FUSER ERROR indicates the incorrect fuser is installed, and not a general fuser failure.

If the fuser's sleeve does not spin when you manually turn the gear,

please do not assume that the fuser will not run in the printer. At room

temperature, the grease applied inside the sleeve thickens and may actually

prevent the sleeve from spinning. When the fuser is installed and run in the

printer, the grease will heat up and attain proper viscosity.

About Metrofuser Metrofuser is a leading global innovator, manufacturer and marketer of printer parts, equipment, diagnostics, repair information and systems solutions for professional users performing critical tasks. Products and services include remanufactured laser printer parts, remanufactured printers and printer repair training for HP, Lexmark and Canon brands. The company's customers include office equipment dealerships, online retailers, repair centers and MPS service providers nationwide. Metrofuser has been named to Inc. Magazine’s fastest growing companies five consecutive years. For more information, visit


bottom of page