THE CULPRIT IS CAUGHT! This poly cap which is in series with the bridge rectifier input is reading at only 55% of nominal! So the rectified voltage is too low to actually trigger the relay coil! Can’t believe I didn’t test this much earlier
Spent the last few hours reverse engineering the schematic and checking it. Any suggestions for possible culprits? The relay isn’t switching on. Sorry I forgot the silicon rectifier part number. R3 and R4 are 1-2W, others are 1/4W. Ignore scribbles on the bridge rectifier I drew diodes wrong at first.