TM9-8030 outlines the use of the light switch and the various positions. I'll use this as my guide. For those following along with our home game I'll post a picture of the light switch from the manual.

Turn on Service headlights: lower right switch to position F and simultaneously move upper lever to position E. This works. Headlights come on and I can switch between high and low beam.
Turn off service headlights: upper switch to position C, and lower left switch to J. Nope. I have to move the lower left switch to position H, and then my panel (dash) lights and marker lights (which are now turn signals) come on.
This is about all I can do. I can't turn off all the lights on the truck. I can turn off some of the lights, but not all of them. Before I started playing with the light switch to assess the light situation, all lights were off. Also, my unlock switch doesn't seem to move anymore. It's stuck in the "lock" position.
What's going on here that I am not understanding?