I would say get a new flasher. My grandpa found an old Volvo 6V flasher can in his barn. Works and fits perfectly, and you can hear the flasher clicking while the engine's running. Probably something like this flasher would work. But you'll have to find out which two prongs make the lights flash. Pretty much any flasher can that's 6V would work.
Do you have the stock airbox, aftermarket air filter, or none?