HP OfficeJet Pro 6958, 6968, and 6978 Carriage Jam: Printhead Stuck on the Right and Printer Error/Jam Fixes

Question

I'm having a problem with my HP OfficeJet Pro 6958, 6968, or 6978 that seems similar to a carriage jam or printhead stuck on the right side. The gear appears to be in place, and when I manually turn the wheel, the tray moves backward and forward without any issue. Once I do that, the printhead carriage can move side to side. However, when I let the printer try to do this on its own, it gives a printer error or jam message. It seems like the carriage is not being released or allowed to move unless I manually move the mechanism. What could be causing this?

Answer

Based on your description, the fact that you can manually turn the wheel and make the tray move backward and forward is an important clue. It suggests that the mechanical linkage is not completely broken or frozen. The gear is present, and the movement path is not totally blocked. However, because the printer cannot perform the same movement by itself, the problem may be with the drive system rather than the carriage alone.

One likely cause is a weak or failing PF motor. The PF motor, or paper feed motor, is responsible for driving part of the printer's mechanical movement. In this type of HP OfficeJet Pro printer, the paper feed system and carriage release mechanism are related. If the PF motor does not have enough torque, it may not be able to move the tray or gear system far enough to properly unlock or position the carriage. When you manually turn the wheel, you are doing the motor's job for it, which is why the carriage can then move side to side. But when the printer tries to do the same thing on its own, the motor may stall, slip, or fail to reach the expected position, causing the printer to report a jam or general printer error.

This can happen even when the printer does not have a visible paper jam. A "printer error," "carriage jam," or "paper jam" message does not always mean there is paper stuck inside. The printer is watching for mechanical timing and sensor feedback. If the printer tells the PF motor to move a mechanism and the expected sensor change does not happen, the firmware may interpret that as a jam.

For this situation, I would check several areas.

First, inspect the PF motor and its drive train. If the motor is weak, worn, or partially failing, it may still make noise or attempt to move, but it may not have enough strength to complete the cycle. A motor with low torque can behave exactly as you described: the mechanism works manually, but not under motor power. Also check whether the motor gear is cracked, loose, or slipping on the motor shaft. Sometimes the motor itself is still turning, but the gear is not transferring enough force to the rest of the mechanism.

Second, check for binding in the tray or service station area. Even if the movement feels smooth when you turn it by hand, the printer motor has limited torque. A small amount of resistance can be enough to stop the motor from completing its cycle. Look for dried ink buildup, debris, broken plastic pieces, warped parts, or anything rubbing against the moving tray. The service station or capping station area on the right side of the printer is a common place for ink buildup. If the printhead parks on the right and the carriage gets stuck there, the service station may not be retracting or releasing correctly.

Third, check the gears involved in the release mechanism. A missing tooth, cracked hub, or gear that has shifted slightly out of position can allow manual movement but fail under normal operation. When turning the wheel by hand, you may unknowingly apply more force or move it more slowly than the printer does. The printer motor, however, expects the mechanism to move in a precise sequence. If one gear skips, slips, or fails to reach the correct end position, the printer may stop and report a jam.

Fourth, check the carriage path. Once the carriage is released, it should move freely from side to side with minimal resistance. Make sure the carriage rail is clean and lightly lubricated, and inspect the encoder strip behind the carriage. A dirty encoder strip can confuse the printer about the carriage position, although your description points more strongly toward a release or drive problem than a position-reading problem. Still, the encoder strip should be clean, properly seated, and not twisted or dislodged.

Fifth, inspect the carriage lock or printhead parking mechanism. Many printers lock the carriage when the printer is powered off or when the printhead is parked. During startup, the printer must release that lock before the carriage can travel. If the release mechanism is not being moved far enough by the PF motor, the printer may think there is a carriage jam. Since you said the carriage can move after you manually turn the wheel, that points toward the carriage lock being mechanically capable of releasing, but not being released by the printer's motorized sequence.

In short, your diagnosis is probably correct that the carrier is not being allowed to move until you manually assist the mechanism. The most likely reason is that the PF motor does not have enough torque, or the motor's drive path has too much resistance. I would focus on the PF motor, motor gear, related drive gears, and the service station/tray mechanism that the motor is trying to move. If everything moves smoothly by hand but fails under printer power, a weak PF motor is a very reasonable suspect.

If the printer gives a general "printer error," "carriage jam," or "paper jam" message, those errors can all be triggered by the same underlying problem: the printer attempted to initialize the carriage or paper feed mechanism and did not detect the expected movement. Even though the message may say "jam," the real issue may be a weak motor, slipping gear, stuck service station, or failed mechanical timing.

Addressing printer issues can be a complicated affair because many of these problems require hands-on inspection. For that reason, we're not able to provide remote troubleshooting, personalized repair suggestions, or ongoing support for printer repairs. We do offer an in-person evaluation and repair service through our local diagnostic facility, available here: BCH Technologies Printer Repair Service [https://bchtechnologies.com/printer-repair-service]. Because demand is high, we operate on a first-come, first-served basis, so it may take a few weeks before we can accept your printer for drop-off. Our services are structured to repair either a complete printer or specific printer parts, with instructions provided on how to proceed. However, we understand that our rates may not be the most economical option for every situation. For that reason, we strongly recommend self-help through online research whenever possible. A good place to start is YouTube, including our homepage at BCH Technologies on YouTube [https://youtube.com/@bchtechnologies]. Use the search icon next to the "About" tab on the right-hand side of the channel menu bar to search for specific topics. I receive dozens of questions every day asking for videos on particular printer problems, and after making videos for the past nine years, it is difficult to remember every single one. YouTube's search function is usually the fastest way to find the most relevant video, and it may also recommend helpful videos from other channels.

Thank you again for reaching out and for supporting BCH Technologies. I hope this helps point you in the right direction. In your case, I would pay especially close attention to the PF motor and the mechanism it drives, because the printer's ability to work only after manual assistance strongly suggests a torque, gear, or release-mechanism issue.