For this issue that you are experiencing with this Slingbox, is necessary to confirm if the trouble is with the Slingbox hardware or maybe just the video cables that you are using. Have you tried different cables? Can you connect the Slingbox using coaxial or S-video to check if the issue persists. If you change the cables and the issue persists it means that the Slingbox needs to be replace since you already Reset the Slingbox to factory settings.
Hope this helps