Change Gear (520/521/590/591

OKI Change Gear 4PP4025-3340P001 is a drive gear for the mechanism in compatible MICROLINE dot-matrix printers. The exact part number is identified as a change gear in OKI parts listings, including the printer-unit listings for ML3320 and ML5520.

It is listed for ML3320, ML3321, ML3390, ML3391, ML520, ML521, ML5520, ML5521, ML5590 and ML5591 models. This replacement component is intended for printer maintenance when the corresponding gear needs attention. Its defined role in the mechanism makes it a focused spare part for servicing the listed printers.