Dead Thunderbolt Port on Macbook Pro
I have a 2013 Macbook Pro with two Thunderbolt ports on the left side. Both appear to be dead. This happened suddenly. Two days ago they were both working, though they were having some issues--screen lag and other things. It felt like they were dying.
The reason I suspect the ports on the Macbook rather than on the connected device is this: I have two LED Cinema Displays. When I plug either display in, the USB connection works, but the Thunderbolt connections won't. It's unlikely that two different display Thunderbolt connections stopped working simultaneously.
So...how can I fix a dead Thunderbolt port on a Macbook Pro? I've tried rebooting both PRAM and SMC. Any other suggestions?
Macbook Pro 3.06 GHz, Mac OS X (10.6.2)