Epson ET-8550 Error Code 034004: Missing Internal Parts and How to Fix Paper Jam Detection Issues

Question:
I purchased a used Epson ET-8550 printer, and I’ve noticed it’s missing a cover inside. The printer displays error code 034004 and refuses to operate. I’m not sure what part is missing or how to identify it. I’m also not local to your shop, so I’d appreciate any tips for diagnosing and possibly repairing the printer myself. If you know the part number or have a used replacement part, please let me know.

Answer:

Understanding Epson Error Code 034004

Error 034004 is classified by Epson as an "insoluble paper jam error." This doesn’t always mean there’s paper physically stuck—it can also be triggered by mechanical faults or missing components that disrupt the printer’s internal logic and sensor readings. Here are the most common causes of this error:

• Foreign Objects in the Paper Path: Even tiny obstructions like label fragments, foam, or stray pieces of tape can trip the sensors.

• Misalignment or Bent Frame: If the printer was handled roughly or partially disassembled, the internal chassis might be bent, interfering with paper movement or sensor alignment.

• Broken or Misaligned Change Lever: The ET-8550 uses a paper path selector lever to switch between front and rear feeds. If this lever or its internal guide is missing or stuck, the printer may be unable to recognize the correct path, causing the 034004 error.

• True Paper Jam: While it may seem obvious, paper jams that occur deep under the carriage or behind gears are easy to miss but can still trigger this code.

Since you mentioned that the printer is missing an internal cover, this might be central to the issue. Epson machines rely heavily on exact part placement. If a part such as a paper guide, change lever shield, or feed sensor cover is missing, the sensor system could misread conditions inside the printer—causing a halt during startup or printing.

Next Steps for Diagnosing and Fixing the Issue

Here’s a structured way to move forward:

1. Photo Assessment
   If you can send us detailed images of the printer’s internal areas—especially where the missing cover should be—we’ll help identify:

   • What part is missing

   • Its function

   • The correct part number

   • Whether we have it in our used inventory or if we can direct you to where it’s available

2. Install Ink
   Once the mechanical issues are resolved, the printer needs to detect valid ink before it can complete its initialization process. We recommend using fresh ink tanks—not reused or partially used cartridges from other machines.

3. Clear Potential Obstructions
   Open all access points and inspect under the printhead carriage, around the rollers, and especially the rear feed mechanism. Even a small piece of debris can cause the sensors to register a jam.

4. Realign the Change Lever Mechanism
   If the paper source selector lever is not returning to its correct resting position or is missing its spring or guide, the printer may be stuck trying to feed from an unrecognized path.

Remote Support Options

Although you're not local, we’re happy to support you remotely through detailed photos, diagnostics, and guided instructions. In addition to email support, we occasionally offer one-on-one phone consultations for more complex walk-throughs (entirely optional).

Please send over the photos whenever you're ready. That will allow us to provide an accurate assessment and direct you toward the right part or repair step.

Important Note About Repairs and Our Services

Printer repairs—especially involving internal parts—can be challenging without hands-on access. For this reason, we're unable to provide in-depth remote troubleshooting for complex mechanical issues. However, we do offer in-person diagnostics and service through our printer repair facility (https://bchtechnologies.com/printer-repair-service).

Please keep in mind:

• Repairs are processed on a first-come, first-served basis and may require a few weeks before drop-off is possible.

• We offer both full-printer and part-specific repair options, with detailed intake instructions.

• While our service may not be the most budget-friendly, we encourage DIY solutions whenever possible.

For self-guided help, check out the BCH Technologies YouTube homepage (https://youtube.com/@bchtechnologies). Use the search icon beside the "About" tab to find content related to your issue. With hundreds of videos in our archive, there's a strong chance you'll find something helpful—if not from us, then through suggested videos from other creators.

Thanks again for your thoughtful message and for trusting us with your Epson ET-8550 project. Once you send over those photos, we’ll continue working with you step-by-step. Let us know anytime if you have other questions or need help sourcing compatible parts.

Looking forward to helping you get your printer back in working shape!