Lionel 154 Signal Accessory Problem

Maybe I misread, but did you try holding the unit upside down, and applying power directly to the lead that goes to the side that isn't lighting (with a neutral wire attached to the frame)?  If it's still dead (with a good bulb), then maybe try gently scraping the inside of the bulb socket with an x-acto knife.

Good luck; the 154 is a great accessory...

Thanks for the suggestion; no, I did not try either of those things, but will do so.  I've since noticed a little bit of rust on the metal ring behind the socket so will try cleaning everything up also.  Appreciate the help.

Most times it's the ground.  That would be the lamp housing- try a light sanding of the socket using a dowel w/ medium sandpaper wrapped around it.  Then look at joints that connect the ground side, Lionel and others used crimped steel joints to make ground connections.  If any are loose, that could be the issue, and a simple squeeze could re-establish that connection.

Thanks much; in the process of sanding it I found the wire in the back of the socket was broken.  I soldered it back on but it still isn't working.  But I really appreciate the responses here.  Everyone is always very helpful.