How should I fix the marker light on my GG1?

Red marker lamps should light opposite the headlight.  If you have to open the locomotive to change the bulb you might as well look at the wiring.  It should be relatively easy, of course I’m not doing it.

Most of the time, they light opposite the direction of travel.  I just finished repairing a couple of K-Line F3 sets, and that's how they work for them.

I will say that most of the manufacturers way back when didn't have any rhyme or reason to the color or behavior of the lighting.  Even folks like 3rd Rail had red class lights on the steamers...

The K-Line GG-1 that I have operates identical to yours.  The red lights go on with the headlight in direction of travel.  Mine is the low bucks version without even a horn.  I assume that is how the lights were designed to operate in that particular engine.

I just realized what you guys have.  That's the way they're wired, all the lights in the forward end go on together.  When you change directions, all the lights in the back go on.  I forgot momentarily this is the K-Line GG1.

So, change the wiring around so that the red lights at one end are powered when the headlight at the other end is on,and vice versa.  Unless the lamps in question are mounted on circuit boards, or otherwise difficult to access, it seems it would be easy, but (as Dan said) "I'm not doing it."

It is easy, I’m almost done! It’s just grain-of-wheat bulbs. There’s one for each marker and one for each headlight making 3 bulbs total on each end. I just connected the front light and rear markers to the front light harness, and the rear light and front markers to the rear light harness...

An added bonus is that the dead marker wasn’t dead- the bulb had just fallen out of the holder and was not shining into the marker...

Steaming Jon - I had never given it a thought to update the headlight/marker light arrangement on my GG-1, as I like to keep most engines as they came from the factory.  Now you have gotten me interested in doing the "fix".