And just more photos overall. I notice that you have no #8 nuts securing your power transformer, and there may be other things in the build causing problems.
Another test you can do is to heat up and remove all the wires connecting that board to the circuit, then flip the board around. If the side of the board causing problems continues to cause problems, then we can zero in on that half of the board. If that half of the board works hooked up to the other half of the circuit, then there's a problem with the build under the Speedball.