ONLY-left turn signal mystery

[abcounts]

I drive a 2002 996 Cabriolet with 6 speed transmission. I was driving with the top down no lights on when I used the left turn signal, and it started blinking very fast. I pulled over to examine my lights and discovered ONLY the left turn signal was not working. I replaced the bulb with a new one, cleaned up everything as I went along, but it still does not work and it is only this single bulb which does not light. I checked the fuses which all seem to be very good. I replaced the relay with one I got from auto zone (Novita EP36) which caused the very quick blinking to slow to normal speed, but still no left turn signal.  So, I put the old one back, and I've ordered Wherle brand from Pelican Parts. I will wait 5 days till I get that one to check. I've cleaned around the bulb socket sprayed with CRC electrical cleaner, stretched the contacts so they make a solid connection, but still ONLY this single bulb does not work. I also examined and spray cleaned the head lamp "Pin" connector and could not see any damage. I've also removed and cleaned two ground contacts on the car body near the front wiring harness. I also used my durometric reader and detected no faults, but as far as I can tell, it (the Enthusiast version) has no way of checking this particular circuit. I would like to emphasize that the signal stalk appears to be working very well. I drive it and it returns in both directions and all of the light switch functions also appear to be working well. So any help would be greatly appreciated. Is there anyway to isolate this for bulb for testing while in the headlight installation? Can I test to see if electricity at the pins is getting to this particular bulb?  It must be reaching all the others cause they are all working. Can I test to see if electricity is reaching the individual pin?  I've removed the inside wheel well cover to check to see the pins are seating properly including the suspected A1 pin.  They appear to be fine. What am I missing? Thank you. 

[abcounts]

Sorry. I forgot to say these are Xenon Litronic headlights. Thank you again.

[DBJoe996]

Did you check both the front and REAR left turn signal bulb?  Could be one or both.

[abcounts]

Thank you. I have checked the rear. It seems very good and actually works but blinks very fast like the dash arrow. Since then, I switched the front bulbs (with the sockets attached this time) and now the left side works fine and the right does not light and flashes on the dash very rapidly like the left did before.  I am thinking it is the socket itself and have ordered one from Pelican. It will take a few days till I receive it and can tell for sure. I'll update if it works or not. Thanks again.

[abcounts]

OK. I received the new socket from Pelican, put it in and everything is fine with the world. In hindsight, I didn't think the sockets were interchangeable between headlights, or that no obvious signs of wear would prevent the socket from working. So one of the earlier steps in diagnosis should be: If the new bulb doesn't work, try moving the bulb with the socket to other side headlight. It was the socket that was bad. 

[Loren]