Atwater-Kent cap replacement advise needed.

[Electronic M]

455KC? That is an IF frequency! This set is a TRF not a superheterodyne so it should not tune or respond to 455KC. Unlike the superhetrodyne sets that were the norm in the octal tube era; TRF sets do not have an IF system nor a converter/mixer osc system. A TRF basically takes the antenna input, filters one station with a coil and a variable cap, and sends the signal to an amplifier. Which, from there, feeds as many additional stages of identical inductor-capacitor filters and amplifiers as there are tubes between the first tube off the antenna and the detector.

That large can with all the wires going to it, I believe is the power supply, and should not be messed with unless the hum is really bad or one of the supply voltages is significantly off.