WTH diode in Lionel 0-8-0?

Classic Toy Trains Forum
1

While exploring one of the current (but presently inoperative) 0-8-0 starter set locos, I discovered a small diode buried under some of the shrink tubing. It appears to be a zener, but now I can’t tell because it broke in half due to some oafishness on my part. It is connected across the bundle of “ground” wires and the lead to the headlite. Anyone know what this is so I can get a replacement? Naturally there are no schematics available from Lionel…

Also found a 750 ohm resistor between the “ground” bundle and the “hot” bundle; what would its purpose be?

2

What sort of headlight does it have? That might be a clue.

3

Don’t they have a constant voltage headlight? That might be what it is for. I think mine has a LED headlight.

4

It appears to be an LED; so the diode is for half wave rectification then, and not a zener? What value do you think it should be?