I'm going to try and post links to the pictures.
Loop pumps photo is
here. This photo shows the pumps and the BX with the wiring.
Left side of control board photo is
here. This photo shows the left side of the control board. The yellow and orange wires attached to the terminal blocks just left and below the center of the picture come from the box with the two 7A circuit breakers. The beige block to the left sitting on the bottom of the compartment is the free-floating (not screwed down) transformer(?) that caused the short when I tried moving it around to follow the wiring. The red tag at the top of the image is attached to wires (not connected) that are for the hot water generator.
Closer view of terminal blocks and transformer is
here. The orange and yellow wires coming from the circuit breakers are the only ones attached to the terminal blocks.