Question about vintage Winker plugs [View all]

I found 4 vintage Winker plugs. They look new. I tested them using a modern lamp with a 3 way bulb. I had to use a prong adapter because the lamp prongs wouldn't fit into the Winker plug. The adapter prongs did okay. The Winker prongs fit into the plug. The bulb lit, but was dim and didn't blink.
I'd like to test further, to see if the Winker plug will cause the light to blink on and off. I'm not sure if I should use a regular lamp or dig out a string of Christmas lights, and should I try to find a vintage string? I have new strings of lights, not sure if I have any really old ones.

Thanks for any advice