We now know the the Aetna model is 252P under Walgreens. It is a 4-tube + ballast Tuned Radio Freq receiver from 1936. Most of the radios found in this cabinet are 550s, which is a superheterodyne rather than a TRF. The super is relatively rare. The TRF is much more unusual.
With this radio it is best to decide what kind of antenna you are going to use and align the radio to that antenna. A longer antenna will provide the noises mentioned above and a shorter one will make weak stations - weak. While the schematic in Riders says not to bend the plates on the tuning cap, linearity across the band is poor. Maybe someone already bent the plates or maybe they need some adjustment, but the spot (freq) you choose to align to is going to be the sweet spot all else going down hill from there.
No wonder they replaced this chassis with the 550 super.