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I've got one of those sets buried here somewhere in need of restoration. If that radio uses a selenium rectifier (fin looking device), it should be replaced with a modern silicon diode (something like a 1N4007) and a voltage dropping resistor. The electrolytic and paper capacitors should be changed. By the time this radio was made, many paper caps were being made with so called sealed plastic housings. I find that these are just as prone to leakage as their '30's wax covered family members.
Lastly, there is one thing that you should be aware of. This radio likely has a "hot" chassis. What that means is that one side of the AC line is directly connected to one side of the chassis. This poses a serious shock or electrocution hazard. The safest way to work on one of these is to use an isolation transformer. If one is not available, use extreme caution and don't allow any part of your body to touch anything that might have a path to ground while working on the chassis. Try not to even touch the chassis while it's powered up if an isolation transformer is not used.
Most transformerless sets that you find will either have one side of the AC line connected directly to the chassis or have one side of the AC line connected to the chassis thru a capacitor. Zenith seemed to love the direct approach. Many of their tube radios had a printed warning on the back cover stating that one side of the AC line is directly connected to the chassis. This goes for tube and early solid state models.
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