Scans with HP printer are always crooked or skewed - real reason uncovered

[Not-happy-2024]

My M477 all-in-one from 2017 scans crooked or more precisely, skewed vertically, every time. The scanning software has a "Straighten Content" function but it cannot fully correct the skew. This has frustrated me for 7 years to this day.

I was considering buying a new HP all-in-one, thinking that this flaw must have been resolved by 2024. I searched to see if there are similar complaints about newer models. Sure enough there are complaints in 2024 about other models! Apparently this design or production flaw has been baked into other models as well all these years. 

This is a scan by my M477 printer of a spreadsheet grid printed on paper. On the paper the grid is perfectly right angled, but in the scan it is skewed. Note that the vertical lines are aligned with the left edge of the window, but the horizontal lines are skewed vertically. 

This is my discovery: the cause of the skew is a crooked scanning head. In this image, the scanning head is positioned under the glass scanning area by starting the scanning software. The movable scanner head is visibly misaligned with the scanning area. Note that a black gap between the scanner head and the edge of the scanning area is visible at the top of the scanning area, but disappears towards the middle. The apparent amount of misalignment is the same as the skew in the scan of the printout.

The scanner head misalignment is either caused by design flaws with the parts or assembly flaws. All the tech support replies that I've read provide boiler plate trouble shooting steps that cannot possibly resolve this issue since it's baked into the hardware. If HP is not aware of this flaw, they should pay attention to my discovery and avoid it in future products. 

I tried to post images of this issue but get this error message: You do not have sufficient privileges for this resource or its parent to perform this action. If anyone knows the solution, please let me know how I can get around this limitation to post images. 

[Repairatrooper]

The current design, which they have used to several generations is a build it cheaper response. The lack of a solid carriage bar to support the scan head is the real reason and as soon as the scanner has been used a little, the friction difference between the left and right sides causes the skewing. The only real choice is to use the auto skew correction in software but that does not always resolve the issue. Wait till your fuser fails at 40K pages. Design life of the engine on this series is 50K. I have seen some go twice that but have seen a lot more with delaminated fusers at 35-45K. If you do a lot of document scanning and do not need a flatbed, the best choice is either a brother 4700 series or a Ricoh (formerly Fujitsu) scanner. HP also makes a straight pass through document scanner so there are choices.

[Not-happy-2024]

Thanks Repairatrooper for confirming that the crooked scans are caused by a misaligned carriage bar. Considering the number of other posts about this issue, it has been frustrating a lot of users for years. It is due to a poor mechanical design that HP keeps using in multiple models. The "Straighten content" function in the software only partly corrects the skew. Indeed the only solution is to buy another brand of scanner.