Hey there! I understand you're having trouble with paper moving back and forth in your Phomemo printer without any successful printing. Let's work through this together and see if we can resolve it.

First, let's check a few basic things:

1. Paper Placement: Ensure that the printing paper is loaded correctly. The print side should be facing up, and the edges of the paper should be aligned with the paper guides.

2. Paper Size Setting: Check that the paper size is correctly set in the app. Incorrect settings can cause misfeeds or jams. You can usually find this option in the print settings within the app you're using with Phomemo.

3. Check for Paper Jams: Although it sounds simple, verify if there are any visible blockages or jams inside the printer. Carefully remove any jammed paper to avoid tearing.

4. Clean Printer Head: Sometimes, accumulated dust or residue can cause issues. Open the printer, take a soft, lint-free cloth slightly dampened with rubbing alcohol, and gently clean the print head. Make sure the printer is off and unplugged while you do this.

5. Close Up the Cover: Ensure the printer cover is properly closed after checking or replacing the paper, as a loose cover might prevent the printer from functioning correctly.

If you’ve done these steps and the issue persists, you may want to try resetting the printer:

1. Turn off the printer and unplug it from the power source.
2. Wait a few seconds, then plug it back in.
3. Power on the device again and try printing.

If none of these steps solve the issue, you may want to refer to the detailed guides from Phomemo like this one here for additional insights.

Let me know how it goes or if you need further assistance!