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Repetitive Defects in Printer Output (print quality problem)

Repetitive vertical defects in printer output is an indication of a problem with one of the revolving parts of the printer that is in contact with the print area of the paper, such as a roller or drum. The most common offender is in the toner cartridge, but other parts could also cause a problem. The key is knowing the distance between the defects.

This will tell you which part is the problem, because the distance indicates the circumference of the part.

HP Laserjet 4000 and 4050

1 1/2 inches (38 mm) Primary Charging Roller
1 7/8 inches (47 mm) Transfer Roller
2 inches (50 mm) Feed Roller, Pre-transfer Roller, Developing Roller
2 1/2 inches (63 mm) Pressure Roller
2 15/16 inches (76 mm) Tray Feed Roller, Separation Roller, Fuser Upper Hot Roller
3 11/16 (94 mm) Photosensitive Drum

HP Laserjet 4250 and 4350

2 1/1 inches (38 mm), 2 3/16 (55 mm), 3 11/16 (94 mm) all indicate a part in the toner cartridge.