My AR-15 has always worked flawlessly firing the 56 gr. Wolf steel cased green laquered ammo. Recently I bought a case of Spanish SS109 NATO ammo (copper cased) and now mysteriously I have a consistent(every single time) failure to extract.

The bolt/carrier cycles but the empty case remains in the chamber and has to be driven out HARD with the cleaning rod.  If I put the empty case back in the chamber and drive the bolt home, I have to kick the charger handle with my heel to get the empty case to extract and eject.

Wolf ammo is 223, SS109 is 5.56 Nato, make sure that your barrel is chambered for 5.56, and not the tighter 223 chamber.

If you do have a 5.56 chamber, then you need to do a bit of cleaning on the barrel.  Start off with soaking the chamber in CLP, then get a 30 Cal mop, soak it in CLP and spin it in the chamber with a few rods and a drill.  What you are after is cleaning the chamber at the last cut before the throat of the barrel.  You will find that it maybe caked with fouling, and causing the SS109 rounds to act as if they were loaded too hot.  

If you still have problems and chamber has tool marks, you will need to polish the chamber.  Basically, the chamber should be smooth as a baby’s ass, with no tool marks or grooves.

Bottom line is the SS109 ammo is showing signs of excessive working pressure (too hot of a load), and binding to the chamber walls. The extractor is being torn from the case rim, but it is not an extractor/spring problem.  If this was the case, the spend case would not need to be pounded out with a cleaning rod.
To recap, check the chamber to make sure it is 5.56 Nato, then clean the chamber, and polish the chamber out if it has tool marks.

Obviously inspecting the chamber and cleaning it would be the first thing to do, as Dano suggested. Did you try to see if other ammo sticks in the chamber ? I assume you meant that the Sapnish SS109 is brass cased, not copper cased. You could have improperly sized brass. Do you have measuring gauges to check ? The simplest thing is to try some other ammo though...

What's to trouble shoot?  It's the shit ammo. DUH!