Thanks for that info, Hoozie. The lights are polar, only work wired one way. I am guessing the resistor is somewhere inbedded in the wiring / leds as I don't see any other kind of component anywhere on the string.

I emailed a company called Mouser, they have a lot of electronic components. Hopefully they have something I can use. If not, I will try your idea of making my own rectifier.