Postwar Lionel 52 Fire Car shorting issue

I assume your flashing bulb is a #257.
First question: is the glass on your 257 bulb the same size as the glass on the #57?
They should be the same, but I have been told that some 257 bulbs were made with larger globes.
If the 257 bulb is larger, that might make the difference.

Another question: Is your 257 bulb US made?
Many imported bulbs have longer bases, which could cause problems in a tight space.

As I recall, neither bulb will fit up into the lens (dome).

As far as I know, the sponge is there to hold the lamp socket.

If I recall correctly, there are two wires running to the bulb socket, one to the center contact, and one to the shell.
The wire to the shell should be attached to the "ground".
The wire to the center contact should be attached to "hot"

If these wires were reversed, that could cause a short.

Hi C.W......I was hoping you'd pop up. This is very baffling. In answer to your questions......the flasher is a 257 and the globe appears to be the same size (I'll get out my calipers later), but neither fit into the globe. I'll check on the bulb length as well.   Everything fits in the shell, but when the shell is compressed downward, that's when the short occurs.  I did not rewire the bulb socket, so I don't think it's wired wrong, but I'll check on what you wrote later tonight.

Your comment about the sponge being for holding the socket makes sense. I can't imagine how that would act as a heat sink (especially when the bulb contacts the globe).

Initially, I thought that the contacts on the bottom of the socket touched the contact plate assembly contacts, so I put electrical tape over it. Didn't seem to help much and if it did, it seems like a silly setup.  My plan (when I was waiting for this car to arrive) was to install an LED in there. That would be an easy fix and would work well, but.......it's not original (although that rarely stops me as I'm not a purist unless I'm working on my more valuable stuff).  I'm thinking maybe I could also look for a shorter socket for the bulb.

Roger

C.W.,

I just calipered the bulbs. Sure enough.....the 57 is around 1 inch long.....the flasher is 1.09 inches long and a touch wider. And it's Chinese made. I don't like the idea that the bulb touches the plastic, so unless I can find a shorter socket, I'll probably order the LED.         Unless there's another way around this.

Roger

Just finished the Fire Car project (see video clip below). The problem was the flashing bulb. As C.W. suspected, the Chinese bulbs are not the right size. It was significantly longer which caused the contacts on the socket to come in contact with the solder tabs below it. So.....I ordered a flashing red 5 mil LED, cut a piece of square styrene that would fit (when Gooped) to the underside of the chassis directly below the red cap. Drilled a hole in the center of it to hold the LED  bulb, wired it up and......it looks and works great!

Roger

The yellow under the cap is a reflection. To the eye it is a total red flash

Roger