We at TinMan3rail recondition lots of switches. Much of our success with this project is thanks to a lot of great advice from this forum. We now include in all our switches LED lighting for the switches themselves and the remote controls. We have not as of yet had 1 request for the old style bulbs.
We stole the technique from one of the later Lionel switches that came with LED's Our circuit is very simple a In1005 diode in series with a 1/4 watt 2.2 k resistor, in series with the LED. For the switches we use a 10mm top hat diode because it throws a lot of light out instead of up. The Switch controllers we use a converted Xmas Led and a grommet. The actual LED's inside are incredibly tiny, but deliver a lot of light due to the super job they did with the plastic covers.
Ok for the newbies I will answer why bother?
First the current needed to run these lights is less than 1/100th what a normal large light bulb uses, and will probably last several lifetimes.
Second, the LED will for our purpose never heat up and melt the lanterns, or eventually destroy the wiring, and does not rob valuable juice from our transformers.
Third, with volume purchasing, the cost of all the components needed to do this is less than the price of one light bulb.
Do we offer these as a kit for do it yourselfers? Sure, the only problem is the installation requires some reasonable soldering skills. This seems to be a disappearing art, in the scheme of things today. If anyone has any interest, I will be more than happy to provide detailed instructions drawings, px, etc., as to "how to do".
We also recondition customer owned switches, and include the LED's in that process. It is very interesting to me that we do these in most cases at a cost very close to what we sell the reconditioned switches for. What seems to be the reason, is the customers want their switches, because they came from a family source or whatever, and are willing to pay the double shipping etc. Interesting nostalgia note.