I love older radio's and the service manuals that are sometimes hard to find. Was able to find a manual quite easily on this site.
Text excerpt from page 16 (click to view)
Disassembly and Reassembly
4-3-3 PCB Removal
1. Refer to the Fig. 4-4. 2. Remove the wire (1P) from the chassis mounting. 3. Pull the PCB guides backwards. 4. Lift both edges of the PCB and pull out.
Disassembly
1. Ensure that the PCB is well positioned in the PCB guides. 2. The power cord must not touch the heat-sink, D73. 3. The PCB guide is part of the chassis mounting ; if a new PCB guide is needed, the complete chassis mounting must be replaced.
4-3-4 SNAPIN Removal
a
SNAPIN-CONTROL b
Fig. 4-7 Press the SNAPIN (b) with thumb ; pull the left holder-bracket (a) with index finger