[GeneBob]

What Bill G said.
The pads are domed and the contacts on the back of the bulbs are domed so it is easy to see a socket contact getting pushed to the side. I spent some time insulating the the back end of the pins where I could but there is not much you can do that won't interfere with the socket. Try chasing your short with the bulbs installed but the power off.
The opposite problem is the ground path from the headlight buckets to the frame. I soldered a wire to the headlight socket and ran it through the conduit to the frame to cure that one.
And Merry Christmas or whatever your Holiday may be.