Hi,
Your Zenith was made 1963-1967. One of the first 2 US FM portable radios made. The -1 suffix indicates AC adapter capability. The first Royal 3000 radios didn't have an AC jack. Don't use the handle as the plastic weakened with age. It breaks easily! Point-to-point handwired and beautifully built in Chicago. The repair tips earlier posters gave you all apply. For manuals and schematics go to
www.nostalgiaair.org!
Cost around $300 new then.