(SOMETIMES, NOT THE BEST OF NEWS)
Every new Zenith portable radio started on an equal footing when they came out of the box. However, over the last 50 years, many radios have seen wear and tear and much damage caused by battery leakage. I have serviced many Royal 500 radios that you wish there were some way of turning back the hands by time to undo the damage.
The Royal 500 series radios were manufactured with an "unbreakable" nylon cabinet. While durable, the cases are certainly not unbreakable. Also, the nylon cases do not respond to commercial plastic scratch removers because of their soft nylon composition. The Royal 500 cabinets can be cleaned and polished; however, there is no way of removing scratches.
Also, the grilles are frequently dented. When a grille is dented, the soft metal is actually slightly stretched. Because of the metal stretch, it is almost imposssible to perfectly reform a dented grille.
The Zenith "lunchbox" radios were made from either genuine leather or a plastic material called "permawear." On many of the lunchbox sets, one had to open the rear cover to access the earphone jack. Those owners who used the earphone, the back flap has been opened and closed many times, contributing to fatigue. There are good quality leather sets around where the earphone jack was not used. Most of the "permawear" sets are in poor condition; although occasionally, one in good shape can be found. Even a permawear cabinet in good shape is fragile and should not be opened and closed often.
My recommendation to Zenith collectors is to first evaluate the cosmetic condition of a radio, including the battery compartment. The electronics can be restored most of the time, but there are cosmetic issues which cannot be reversed. Also, the Zenith radios that are in better cosmetic condition are more desirable to collectors.
But remember, a less than perfect Zenith is always better than no Zenith.