scans come out crooked every time from the document feeder, even if i align the paper perfectly.

Diagnosis

The skewed scans on your HP LaserJet Tank MFP 2604sdw are caused by an imbalance in the friction applied to the leading edge of the paper as it enters the Automatic Document Feeder (ADF). When the rubber pickup rollers wear down or accumulate paper dust and ink residue, they lose their grip. If the left roller has more traction than the right (or vice versa), the page will "pivot" upon entry, resulting in a crooked image. This is often exacerbated by a buildup of debris on the separation pad—the small friction piece that ensures only one sheet is pulled at a time. If this pad is sticky or dirty, it can tug on one side of the page, creating a diagonal pull. You can confirm this by loading a single sheet of heavy cardstock; if the cardstock enters straight but standard 20lb bond paper skews, your rollers have lost the necessary coefficient of friction to handle lighter weights.

How to Fix It

To resolve the skewing issue, you must perform a deep clean of the ADF transport mechanism to restore uniform grip across the width of the page.

1. Power down the printer and unplug the power cable to prevent any accidental motor engagement during cleaning.
2. Lift the ADF cover by gripping the top plastic housing and pivoting it upward to reveal the internal feed mechanism.
3. Locate the primary pickup rollers (the two grey/white rubber cylinders at the entry point). Use a lint-free cloth dampened with distilled water or a 70% isopropyl alcohol solution.
4. Press the cloth against the rubber surface and manually rotate the rollers 360 degrees to remove the "glaze" of paper dust and ink buildup. Ensure you clean the entire circumference of both the left and right rollers equally.
5. Locate the separation pad—the small, rectangular rubber piece located directly opposite the pickup rollers. Wipe this surface thoroughly to remove any adhesive residue or dust.
6. Inspect the paper guides. Ensure the sliding width guides are snapped firmly into the notches of the tray and are not sliding loosely, as even a 2mm gap can cause a skew.
7. Close the ADF cover and perform a test scan with a standard 8.5" x 11" sheet of paper.

If That Didn't Work

• Check for Foreign Objects: Use a flashlight to inspect the ADF path for small staples, paper clips, or tiny torn scraps of paper. A single staple lodged in the left-side guide rail will force the paper to veer right, causing a consistent skew regardless of how well you align the paper.
• Calibrate Paper Weight: If you are using very thin paper (under 60g/m²), the rollers may slip. Try using a higher-grade 24lb bond paper to see if the skew persists. If the heavier paper scans straight, your rollers are likely worn out and need physical replacement.
• Reset the ADF Sensor: Perform a hard power reset. While the printer is on, pull the power cord from the back and wait 60 seconds. This clears the temporary memory of the ADF sensor and can sometimes resolve logic errors in how the printer handles the feed timing.
• Inspect the Platen Glass: Ensure the narrow strip of glass used by the ADF (to the left of the main flatbed) is completely clean. A smudge of grease or a piece of tape on the glass won't cause a physical skew, but it can create a visual distortion that looks like a misalignment.

Heads Up

• Avoid using window cleaners or bleach on the rubber rollers, as these chemicals can dry out the rubber and cause it to crack, leading to permanent slipping.
• Always fan your paper stack before loading it into the ADF to break the static bond between pages, which prevents "double-feeding" and subsequent skewing.
• Periodically check the ADF rollers every 5,000 scans to prevent the buildup of paper dust that leads to this specific issue.
• Ensure the paper guides are snug against the paper but not so tight that the paper bows; a bow in the paper will almost always result in a crooked scan.