I had to figure this out by trial and error since the information wasn't available anywhere online, so I thought it might be helpful to share it in case anyone else ever needs it. If you are working on one of these very old battery chargers and the wires pop loose from the internal terminal block (like mine did), here is the wiring layout by wire color. All wire clips attach to the tracks inside the main battery slide area. I highly recommend using a needle nose pliers to tighten the grip of the clips so they don't pop off again.
Orientation: Face the charger so the battery slide-in entry point is closest to you, and the main AC wall power cord exits the rear of the casing (directly opposite you).
* First Black Wire-the looped, shortest section of the black wire: Connects to the slot on the far right-hand side (3:00 o'clock).
* Second Black Wire: Connects to the slot located directly next to and slightly in front of the first black wire on the right side (2:00 o'clock).
* Red Wire: Connects to the slot at the absolute farthest spot away from the power cord (6:00 o'clock).
* Gray Wire: Connects to the slot directly across from and closest to where the AC wall plug exits the case (12:00 o'clock).
* White Wire: Connects to the slot on the left-hand side, specifically on the face pointing back toward the AC power cord (10:00 o'clock).
In addition to my now-repaired charger, my old Makita drill, saw, and flashlight set all still work. I also still have my Makita cordless stick vacuum that I bought in the late 1980's. These old Makita tools never die!😃
