Disassembly

Remove all 5 screws from bottom panel, then remove panel and battery door. Remove any batteries at this point, as they will probably fall out otherwise.

Remove 4 pcb screws + hex standoff (a 1/4" nut driver works)

Remove 5 jack nuts

Remove all 6 knobs. Note that the selector switch knob is different from the rest (no padding on the bottom). This is the most difficult step. You will most likely need to wiggle a tool below the skirt of the knob, then pull up. Finding the perfect tool is a challenge. Since you have to wiggle something in there, I like to remove all other fasteners first as this tends to give me the most play for this step. Once you get the hang of it, this step is actually easy. Also note there is a metal clip inside each knob. Sometimes this gets stuck on the control's shaft. Look at the shafts are note if any clips got stuck. You'll either need to pull that off and match it with the right knob, or just put that knob back on that shaft.

Remove battery terminals. These just pull straight out.

You can now remove the circuit board.