I’ll directly post the photos here for you, as more people are likely to take a look if they don’t have to leave the page.

Upon quick inspection, I see that using capacitors of incorrect sizes for the PCB could potentially strain the solder joints. (Use caps with 5mm spread) Consequently, I would recommend re-flowing them. I can see some questionable joints on the back of the PCB. I also see some potentially burnt pads containing the electrolytics. Electrolytics should be fully inserted and soldered from the opposite side. When they are up off the board like that they can act like antennas creating unwanted noise.

I would also advise using a Digital Multimeter (DMM) to verify the continuity of all off-board wiring and their connections to eliminate any potential wiring issues. I am not able to trace the wires to the jacks and other off-board connections from the provided photos. Triple check all of your off-board wiring and reflow all solder joints as this is likely the culprit.

Furthermore, some of the off-board wiring appears suspect. I suggest inserting the wire through the pads until it sits flush with the PVC and then soldering from the opposite side to prevent exposed wire.