The FRR/MRR/SRR series receivers are very modular. There are no cables to disconnect -- all connections are fixed on the receiver frame. Great pains were taken to ensure that all modules remained "plug compatible" even after engineering changes. Later versions use solid state diodes in both the power and signal paths, but tube and solid state modules can be freely mixed/swapped between early and late model receivers.
Top view showing BFO, Tuning dial, Xtal Calibrator, 2nd IF, Audio strip and Power supply
Bottom view showing antenna, RF, mixer, HFO and 1st IF strip.