I’m nearing the end of the DC Filament Supply mod install and I’m at the instruction to “attach and solder the twisted pair of wires formerly attached to 22L and 24L to the AC holes on the ciruit board closer to the A side†and then the other pair of wires go to the D side. What sides are these? I don’t see an A or D on the pcb. What side is this instruction referring to? Thanks!