Bachmann steam locomotive lights

[reydel]

I have six (6) Bachmann steam locomotives and their headlights and reversing lights run from great to almost nonexistant. My Climax and American have exicellant lights, My two Consolidations have OK lights but my Shay has very dim lights and my decapode is hardly visible. What is the difference in these systems and can the existing lights especially in the last two locomotives be upgraded?

[SteamGene]

While it might be nice to have all the headlights glow as bright as the other, in the real world, steam locomotives spent most of their lives with the headlight on only at night.  Itd was only with the introduction of the diesel that steamers ran with their light on in the daytime.
Gene