Voltage drop at ballast resistor

Both the make and female those are known as "Packard 56" you can google it. The males have a "tang" on one edge you must release, the female has a tang on the backside. Use a small screwdriver

In the photo below, you would push in the tang which "hangs down" in the lower part of the photo from the "blade" side not the wire side

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Actually for the connector I'm working and a You Tube video I found, I just had to gently squeeze the blade from sides with needle nose pliers and I was able to pull it out. I pulled and cleaned them all. The red and black wires were pretty corroded.