Flatbed scan is clean but ADF scans show thin lines. A partial failure matters: one capability still functions, while a closely related step does not. This guide focuses on isolating that difference in printers and scanners, not on indiscriminate resets. Use the known-good behavior as your control, change one variable at a time, and retest the original scenario after each intervention.
First, reproduce the difference
Baseline test: Scan blank page through ADF and flatbed. Record the current device model, OS or firmware version, and whether this occurs with one file, account, network or source. A reproducible contrast is more informative than a vague message such as “not working.” If the control fails too, stop treating this as a feature-specific problem and investigate the shared dependency first.
Why it can happen
| Hypothesis | Evidence worth checking | Next decision |
|---|---|---|
| Debris on narrow ADF glass strip | Repeat the same action under a controlled alternate state and record the exact difference in outcome. | If the control still works, focus on the affected path rather than resetting the whole device. |
| Scratched scan window | Repeat the same action under a controlled alternate state and record the exact difference in outcome. | If this condition is not present, leave the associated setting unchanged. |
| Sheet feeding causes skew | Repeat the same action under a controlled alternate state and record the exact difference in outcome. | Only escalate to this branch if the simpler comparison did not explain the failure. |
Before any changes
Protect your setup: Avoid abrasive cleaners and liquid entering the device. Check the model guide before opening covers, cleaning parts or changing consumables. Let hot printer components cool and keep original documents available.
Three repair routes
Route A — Correct the observable mismatch
Clean ADF glass strip using model-approved lint-free method. Start only after capturing the baseline. When the recommended control is not present on your model, look for its supported equivalent in the product documentation rather than following screenshots from another version.
Return immediately to the failing task and check whether the outcome changed. If it did, preserve the working setting and avoid piling on additional changes. If it did not, undo the change where appropriate before moving to deeper checks.
Route B — Test the underlying dependency
Compare multiple sheets and inspect glass under safe lighting before service. This advanced comparison is worthwhile only if the simple check did not resolve the problem. The first two possibilities to separate are debris on narrow ADF glass strip and scratched scan window. Do not interpret their presence as proof of a diagnosis; a compatible device and a partially failed service may coexist.
Route C — Handle a limitation or persistent fault
A third explanation is sheet feeding causes skew. Check whether the feature requires particular hardware, account privileges, region settings or source formats. When a feature is unsupported, there may be no legitimate settings-only fix; use the vendor-documented alternative rather than an unsafe workaround.
Step-by-Step Troubleshooting
Follow the Beginner steps first. Advanced steps are for isolating hardware, application or network-specific causes after a safe baseline test.
Confirm the boundary
Flatbed scan is clean but ADF scans show thin lines. Do not assume this is a complete outage. Scan blank page through ADF and flatbed. Keep the account and connections unchanged between attempts.
Capture a useful baseline
Write down the affected model, software version, active input and when this started. Scan blank page through ADF and flatbed. A working comparison tells you which part of the chain is still healthy.
Use the least disruptive correction
Clean ADF glass strip using model-approved lint-free method. Apply one supported change at a time; stop if your model uses a different setting or does not advertise the feature.
Confirm the expected outcome
ADF output is free of repeated vertical lines. Try the original failing action again, not an unrelated easier test; retain the old setting until you know the change helped.
Test the first dependency
Investigate whether debris on narrow ADF glass strip. Specifically, repeat the same action under a controlled alternate state and record the exact difference in outcome. Compare the result with the working baseline from the beginner route.
Separate another possible cause
Assess whether scratched scan window. For this branch, repeat the same action under a controlled alternate state and record the exact difference in outcome. Do not change that configuration unless the evidence supports it.
Inspect the third branch
Compare multiple sheets and inspect glass under safe lighting before service. Also consider sheet feeding causes skew. Record the exact point of failure and check product-specific support limits.
Validate and plan a rollback
ADF output is free of repeated vertical lines. Avoid abrasive cleaners and liquid entering the device. If the last change made matters worse, restore it and request supported assistance with a redacted troubleshooting summary.
Verify the result
Success looks like this: ADF output is free of repeated vertical lines. Run this check on the same device and account that originally failed. A different device passing is useful as a comparison, but it does not prove the original issue is fixed.
What to check if it still fails
Before contacting support, collect the exact model and version, the outcome of the baseline test, and whether the controlled correction changed anything. Keep passwords, private media, account identifiers, serial numbers and network keys out of screenshots or shared logs. Avoid abrasive cleaners and liquid entering the device.
Solution Checklist
When to seek model-specific support
If the supported correction does not work and sheet feeding causes skew remains plausible, stop before a destructive action. Provide the vendor with the baseline from this guide and ask whether the exact hardware and software combination supports the requested behavior.