Laser Jet M277 Printing Magenta Splatter

[WOLLAM]

Very puzzling problem.  Our laser jet is printing "splattered" magenta in a 2"-4" swath along the top of the page.  I have checked/cleaned the toner cartridges, checked the toner trays, rollers, calibration, etc. Nothing seems to correct the problem.  The puzzling part is this: the splatter ONLY appears when the document being printed is a black/white document.  If the document has even just 2 words with a colored font there is no splattering.  In my test document I changed two words to have a red font, document came out perfect.  I have tried printing b/w documents from Word, Excel, and web pages...they all have the splatter.

Any help and/or insight will be greatly appreciated.  Thank you in advance.

[Repairatrooper]

If the defect looks clearly like magenta then likely you are having some type of issue with the magenta cartridge that becomes obvious when the cartridges are alienated (deactivated from the print path for black only printing). Our first step would be to either disable the cartridge check and move the cartridges around or try another magenta cartridge.

[WOLLAM]

I am trying to avoid the prospect of purchasing a a new cartridge as all 4 of the cartridges are at 80% or better.  I am not familiar with what you said about "disabling the cartridge check", but next I will try switching the cartridges around.  I'll post the results after the test.  Thank you.

[WOLLAM]

Hello Again,

So I disabled the cartridge check and switched the magenta and cyan cartridges but the printer would not print any document.  It gave the error that cartridges were not in the correct positions.  Upon inspection of the cartridges I noticed all except the black had some amount of magenta dust on the roller.  Short of taking apart the cartridge to inspect the "toner reservoir" for defects I can't think of anything else to check or try in an attempt to repair.  As stated earlier, I'd prefer not to buy another cartridge.  Also, This may have something to do with the construction quality of the actual cartridge...they are not HP brand.

Again, any help would be greatly appreciated.