I continue to repair and try to make as nice as possible my R1313.
Today I diagnose why the interior lights no longer work.
It turns out the switch arms that make the electrical circuit over time loose their ability to make good contact.
So I came up with an idea and solution.
I needed to raise the height of the center contact strip.
Turns out I had some very thin silver, I cut some small pieces , bent it to fit, and used a hot glue gun to hold in place on the side that makes contact with the bulb holder.
Now the lights work again and I think this is cheaper than a new light.
I hope I am clear and the pictures help.