My GSA 4120b died a couple of weeks ago...
Took it to an LG service centre and left it with them, got a call about 10 days later telling me to come and pick up my new GSA 4166b..
Yey for 2 year warranties, my old drive was about 18 months old.
Drive built Dec 05 with 1.02 firm.
So far it has done flawless burns on DVD-R media at 16x in about 6 mins.