Laserjet pro MFP m277dw leaves a black line on scans from ADF tray. The debris is under the glass.

[McMaccy]

Can anybody provide instructions and guidance on how I can get underneath the ADF scanner glass to remove debris? That debris results in a vertical black line being generated on each and every page scanned via the ADF feed.

Thanks in advance

Andy

[OsSt]

Is the debris on the glass itself or is it on the scanner assembly bottom? 
If the glass itself is dirty than yes it will cause issues. 
On this model, to remove the glass, theres no real option without slightly mess up the plastics. The upper part of the scanner unit is glued in with doublesided tape. First you need to remove the ADF system, then theres torx screws.
Before disassembling the unit, be sure to clean the glass with alchohol. Maybe the issue is only with the surface being dirty and just not seeing it.

[McMaccy]

Hi;

Thanks for coming back to me so quickly. 

The ADF glass that I'm referring to is not that of the ADF unit in the hinged-'lid'. It's more the strip of glass to the left-hand-side of the main flatbed scanner glass. The debris is underneath this - I have no clue how it's got there!? And yes, all scanning surfaces have been cleaned as directed in the HP knowledgebase video on cleaning the scan-surfaces. That's when I noticed this debris.

Andy

[OsSt]

Yeah, is actually the debris stuck on the glass itself or is it beneath the glass? Because the dirt that's on the plastic assembly cannot cause any issues. Did you really cleaned the small glass on the left side? With alcohol? Because there been at least couple of dozen times a client of mine tells me he cleaned it, I get in to the car, drive for an hour just to clean the glass for like a minute 😄

If the dirt is actuality stuck to the glass but from the underside than yes - you will need to service it or disassemble it yourself if you're confident and comfortable to disassemble the printer  

[McMaccy]

The debris is underneath the glass. Hence me requesting guidance/instruction on how I disassemble the unit to access it. I'm an IT support supervisor by trade and am comfortable disassembling electrical equipment. But I also want to ensure that I don't accidentally damage the unit (which I know can be easy to do from past experience).

Andy

[Valsimot]

The screws are on the bottom part, you need to remove the complete scanner from the printer, turn in upside down or from underneath access screws and disassemble it.