It also looks like they aren't perpendicular to the wheel set.
I would try getting them to sit at a perfect 90° to the wheels, as well as removing the pickup for a test to see if that's the issue at all. Rounding or chamfering the contact tips might help too.
Check the plastic surface that acts as the axle bearings. Clean the loco wheels and track to rule out oils, and throw some test weight on top of the loco too.
My G's weren't lit. I removed the roof screws so I could take the tops off at will and toss in some cheap $1 store solar LED garden lights for pathways.
Going to batteries is another option. Even craft stores might have battery clips for a 9v holiday quick fix. An RC hobby shop or electronic supply for sure.
