How to Fix False Paper Jam Errors After Installing a Drag Chain on the Epson ET-8550

Question:

After installing a drag chain on my Epson ET-8550, the printer started displaying a paper-jam error-even though there's no paper stuck inside. What could be causing this, and how can I resolve it?

Answer:

Regarding your issue: a false paper jam after installing a drag chain on the ET-8550 is a common occurrence, especially when performing tubing or drag-chain modifications. Since your error appeared right after the installation, the problem is rarely caused by actual paper-it's almost always caused by interference with the carriage system or one of the internal sensors.

1. Why the ET-8550 Thinks There's a Paper Jam

The ET-8550 uses several internal sensors to detect paper movement and carriage motion. After adding a drag chain, one of the following often happens:

• The drag chain physically strikes an internal component
  This is the most common cause. If the chain bumps or restricts the carriage, the printer interprets the resistance as a jam.

• The drag chain prevents the carriage from reaching its home position
  When the carriage cannot fully park on the right side, the printer cannot complete its initialization sequence and throws a paper-jam or 000025 transportation error.

• A cable or tube presses lightly against a sensor flag
  Optical sensor flags near the paper path are very sensitive-anything obstructing their movement can trigger a false jam message.

2. What Error Codes You May See

Depending on exactly where the interference occurs, you may encounter:

• Paper Jam Error - generic obstruction warning

• 000025 Transportation Lock Error - indicates the carriage couldn't move freely

• Carriage Jam / Carriage Cannot Move Error - triggered when drag chain or tubing restricts motion

Even though your printer only reports a paper jam, internally the cause is usually carriage-related.

3. Key Areas to Inspect

Here's where to look:

✔ A. Position where the carriage stops moving

As you mentioned, the drag chain likely hit a bracket, guide rail, rear panel rib, or part of the frame. Slowly move the carriage and watch where:

• The drag chain bends

• The chain catches

• The chain pulls or pushes too tightly

This is the primary diagnostic step.

✔ B. Check the chain mounting angle

If the chain sits too high or too far inward, it collides with the underside of the scanner assembly or with the left/right frame posts.

✔ C. Verify tubing length and slack

If the tubing is too short or too stiff, it can pull the carriage back prematurely and trip the sensor sequence.

✔ D. Inspect the rear ASF (Auto Sheet Feeder) sensor flag

Tubing routed too close to the back wall can nudge this tiny flag, causing instant false jam errors.

4. How to Fix the Issue

Below are the most effective corrective steps:

A. Reposition the drag chain

Shift the chain slightly outward or lower to ensure it clears all internal obstacles during carriage travel.

B. Adjust the chain starting point

Mount the chain a few millimeters further from the carriage so it folds smoothly without bumping components.

C. Add or reduce tubing slack

You want enough slack for full carriage travel but not so much that the bundle bulges or presses against sensors.

D. Run a manual carriage travel test

With the printer off, slide the carriage slowly from left to right:

• No bumps

• No scratching

• No points where the drag chain tightens

If you feel any resistance, that's your jam trigger.

E. Re-tape or re-anchor the tubing

Use soft tape points to guide the chain's bending path away from sensitive areas.

Once the drag chain moves cleanly with the carriage, the paper-jam error typically clears on the next startup.

Addressing physical printer issues-especially those caused by modifications-requires a hands-on inspection, so we're unable to provide remote troubleshooting or step-by-step guidance. We do offer in-person diagnostics and repairs through our local shop: BCH Technologies Printer Repair Service (https://bchtechnologies.com/printer-repair-service) [https://bchtechnologies.com/printer-repair-service]. Because demand is high, service is first-come, first-served, and it may take a few weeks before your printer can be checked in. We repair both entire machines and individual components, though our service rates may not be the most budget-friendly. For detailed self-help resources, visiting our YouTube channel homepage-BCH Technologies on YouTube (https://youtube.com/@bchtechnologies) [https://youtube.com/@bchtechnologies]-and using the search icon beside the "About" tab often provides the fastest way to find specialized videos. YouTube may also recommend content from other creators that could assist you.

Thank you again for contacting us and for your support. Please feel free to reach out anytime you need more guidance.