This is just about the round "pop out" type hazard switch.
I wonder how many of us have paper/part of a match/a small screwdriver wedged in the side of the hazard switch to stop it "popping" of it's own accord?
Mine started doing that so I found a "lightly used" one on eBay, which 6 months later started doing the same thing .... so I stumped up some $ for a NOS one.
Sitting on a conference call this morning my gaze fell upon the original switch sat on my desk - complete with a small wedge of wood to keep it in place. I'd always shied away from taking it apart. The extra capacitor solder on the outside didn't bode well for the anticipated electrical gubbins inside. Anyway - given I'd got two spares... I gently prized apart the switch.... and .... well... it's really basic!
There's an arm with a pin in it on one side ... and it appears to be that arm which needs a little bending to make better contact with the switch center (the bit that you push)... reassemble... and all is good.....
.... and I've now got three good switches...

A