The discriminator IC of the Albrecht AE55H and the identical GRE PSR-255, a Motorola MC3361, is hidden below a crystal (marked 10.245). By bending this crystal carefully upright, the MC3361 can be reached.
The unfiltered audio can be found at pin 9.
A 10 k resistor is soldered to pin 9, and mounted next to the IC. The resistor's other lead is isolated, e.g. with a piece of insulation stripped
from insulated wire.
As usual with the 3361, the discriminator output contains a strong IF component at 455 kHz. This is filtered by mounting a 2.2 nF capacitor with one lead to
the 10 k resistor, and the other lead to ground. The metal shield of the IF coil nearby can be used as a ground contact.