I need to replace led headlight in my climax.Can just the LED be replaced or do I need to replace housing with LED?

The geared axle in rear truck of stearns heisler turns stiffly with gearbox/driver assembly in frame.With gearbox removed driver turns freely in frame.Gearbox with axle assembly turns freely outside of frame.When gearbox is installed in frame driver turns very stiffly.Any ideas?Does the new heisler truck come with gearbox I can't tell by picture.

I am adding detail parts to On30 climax and want to paint them a matching black rather than paint the whole loco.Anyone done a color match,and what paint was used?