The eBay API token needs to be revoked on the user's MyeBay page and then re-created via Linnworks.

 Here are the steps to revoke a token:

- Log in to eBay
- Go to My eBay
- Under My Account, Click on Site Preferences
- On the Site Preferences page, look for Third-party authorizations
- Select the Application for which you want to revoke the token - LINN SYSTEMS LTD
- Click Apply

After this is done, you will need to go to Settings -> Channel Integration -> eBay Configuration in and click on 'Test', which will prompt you with a message that the eBay Authorization token has been expired and needs to be re-created. Follow the on-screen instructions to re-create the token and click on "Test" again to make sure that the token has been re-created successfully.