Apparently the bad ones were one particular British brand of mica made in that time period I was told by a British collector. I will have to dig through my emails and find the brand. They were not Philco which mine has. Mica and disk ceramic are the ones that usually survive unless molested or bad luck.
These are simply “small potatoes” in my opinion to worry about including paper capacitors. A couple, yes a couple of Westinghouse 1931 WR-8 Columaire came up for sale nearby and being a sucker for punishment I tend to be, poked my nose into this area making me do some research into these socalled clock radios. OMG!! What a design using an RCA model 82 chassis with everything encased in tin boxes and cans and just for spite poured tar inside these containers as well!! Transformers and capacitors and in order to replace if required, get out the heat gun and face a stinky sticky mess. I’m still pondering to poke my nose into these radios hoping not to get burnt. One is fully functioning but at a higher price and the other has a non functional clock with a damaged face finish. The clock is bad enough but surprisingly a Repro face is available from the US for $29 plus shipping. A weird clock apparently made to work like a pendulum clock so the second hand pulses twice for every second even though it’s electric. We shall see what I’m Phoolish enough to do, a British Philco 444, a Volksempfanger, now perhaps a Columaire?
