Multiple Vertical Lines On Scanned Output - LaserJet Pro 400 MFP M425dn

[Travasaurus]

I ran across this answer accidentally and so I thought I'd share my findings. My HP LaserJet Pro 400 MFP M425dn has been scanning like a charm since "Day 1" and all the sudden, without warning, multiple vertical colored lines started to appear on the image of my scanned documents (and when I say colored they appeared that way in the PDF file, not on the actual printed document of course, which was black & white). Well the 1st thing I did was to clean the flatbed lens glass (which is the only way I scan documents) along with the ADF lens glass and all the other surfaces, as recommended, for good measure. They were all clean as a whistle already, for whatever that's worth, but the problem persisted. I was just about ready to start disassembling the thing when I discovered in some obscure article the suggestion to "power cycle" the unit as part of the troubleshooting procedure. Well first off, the User Manual does not (that I could discover) specifically tell you what "power cycle" is nor how to do it but fortunately a little common sense does, so I unplugged the thing for 5 minutes or so (this as opposed to simply turning the unit off with the power button). I was a bit dubious but lo & behold when I powered it back up the vertical lines were gone! This saved me from a lot of extra work and possible disaster if would've tried to start working "under the glass" so-to-speak. However, I would welcome somebody's explanation as to what might've caused this bizarre problem, since I have never encountered this on any other HP scanner I've used over the years. Truth be told I've never had any problems with such lines even being caused by a dirty lens before, either. Very strange...