There are two series of hazard switch and mostly they spontaneously fail open and will not turn off. This seems to be due to constant spring pressure inside distorting the plastic body over decades. Same thing happens to OEM seat belt buckles. If you shove the button in too far and pin it with a toothpick, it deletes the brake lights. A few owners have 'fixed' their switches by adding a worm-drive hose clamp around the body to squeeze it back in, which works fine.
When mine failed, I took my Series 1 switch apart and shimmed the actuator with a strip cut from a Gary Hall business card! Some hazard switches for FIATs and Alfas interchange but the wire numbers molded into the switch backs vary, so its possible to mis-wire them. The red button unscrews and inside is a garden-variety 3-watt light bulb, replaceable at any Autozone. All this is in a POCA Newsletter- with photos- from decades ago when I fixed mine.