Have just been reading all the threads on this subject. I have experienced some erratic behaviour over the last few days; sometimes they work OK, sometimes they flash twice and stop etc etc...
I have memories of old BMC cars of the '70s and remembered those pesky little brass contacts on the stalk so thought I would try the WD40 trick on the stalk contacts but it made no difference, possibly made it worse. Sought advice of an Audi friend and he changed the relay behind the hazard switch (£25 app) all seems fine now.
Hope someone finds this useful.