If you cannot find anything wrong with your PCB layout and components are good, then you must check for correct waveform on gate of tr4.
Remove tr4 and tr5 from PCB. Or just desolder gate legs and lift them out of PCB.
Put probe and see what waveforms are present on output legs of LM393.
Remove tr4 and tr5 from PCB. Or just desolder gate legs and lift them out of PCB.
Put probe and see what waveforms are present on output legs of LM393.
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