Lazy Central Locking
 

One of the rear doors on my 4.6 has a lazy central locking mechanism. Sometimes it completely unlocks on key fob or dash button but most times it only lifts the button about half way. Locking again and then unlocking usually does the trick.

It seems that something is causing it to stick. I guess it's door card off and get some penetrating fluid in the mechanism unless anyone knows of an easier method.