A mysterious spring

[Pavel]

Hi R4 friends,
Look, what I found sunken thereunder in the left door. A mysterious spring. Have you any idea, where is it from? It seems as from the door lock, but the lock works without it quite good. There is no spring in next door to compare. I didn´t find the spring in the Haynes manual door lock drawing - what you think about it?

 

[angel]

It's the spring that holds the door lock external button to the lock mechanism itslef, without it the locks work perfectly but they may stick in the open position when you push the button all the way in.