6 wires with a two blade flasher is OK. It does look like six wires. And I see the BLK for horn and GRY for indicator light as you said. Looks like 63-66 are the same wiring per this diagram. So the colors should, in fact, match. Follow the tail light wires from rear to brake light switch, to flasher and to turn signal switch to be sure it makes sense.
https://www.google.com/search?q=1963...frGk-YqQ9EE%3D
This is from Jolly's page. If you have not gone there, then go there and read where each wire goes and follow each wire all the way, to see where the problem is. He lists each wire below the diagram.
If you feel that the switch is defective it's your choice to send back, wait for a new one ,and try. I would check the new switch on the bench to see if it works at each lever position. After I checked all of the above.