From FB group
This Zenith Royal 500H radio has the extra 8th transistor for the RF amplifier, so it should have excellent sensitivity and be able to pick up those weak stations. Most of the problems with old radios are with the electrolytic capacitors, but the Zeniths all use the carbon composition resistors and they go higher resistance over time. It’s common to have to replace some to get the radio working.
The other thing is the alignment. I recommend you buy (or make out of wood) a nylon screwdriver that will fit the slugs in the IF cans. Then you can gently tune the IFs to peak them. Never use a metal tool, it will crack the ferrite slugs.
You have a better schematic from the Beitman manual. Print it out and keep it inside of the radio.
Take some soft material like plastic or a wooden toothpick and shape the end like a screwdriver blade. I cut one with a knife and rubbed it on the concrete to sand down the tip.
