Fixed that failed headlamp on wife's car earlier. 1st replacement bulb lasted 2-3 days before it failed. Don't know why, looks perfectly good. Filament appears intact and glass is sparkly clear with no smoking or fingerprints (I made sure not to touch it) so just a random premature failure).
Let's see how long the 2nd replacement lasts. It was bought at the same time as a spare, that's foresight fire you.....
Bad earth somewhere.