Glenn,
the IC type of the audio output stage is LM380N (14 pin) which works with 8 Ohm speakers. Recommended supply voltage between 10-22V.
What is missing? The speaker is polarity sensitive, which means that if you connect it the other way around, the voice coil moves inward and can collide.
Simply swap the wires to allow the speaker diaphragm to move outwards. Does the speaker you installed work correctly in other environments?
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Gyula HA3HZ
HA3HZ