[Raleigh]

To your original question, how could you tell which end of the e-cap part 52 is connected to ground, check where the other end is connected, which is B+, dropped a little by a 15K ohm resistor. Since B+ is the highest voltage in the radio, ground is lower voltage than B+, even with the voltage drop across resistor 48. You would connect the - end of the e-cap to the lower voltage, which is ground.

Note that in this radio, ground is not the lowest voltage, which is always the center tap of the power transformer. That tap is connected to ground through what looks like 257 ohms of resistance, so ground is at a higher voltage. If, say, cap 68 connected from ground to the center tap had been an e-cap, the + lead would go to ground because ground is higher voltage than the center tap.