Coluld be the flasher relay itself going bad. Remember that the hazerds work with the ignition off. I imagine the problem could be there. Some of these old cars have metle covered relays. Solder could get hot enough to move to the side of the circut board and short on the cover. I actually had solder drip off a fuel pump relay on a 240 that I had years back causing the pump to quit. I soldered the relay up and ran it without a cover to keep it cool, and zip tied it out of the way. The solder eventually did the same thing again burning my leg in the process.

john