I've had a Blink J1772 charger for 2 1/2 years (installed before I got my Model S) and it has worked very well. However, yesterday I noticed that it was charging my Model S more slowly. Sure enough, the current had been cut back from 30A to 24A. I unplugged the Blink from the wall outlet to reset it but the problem persists. What are the circumstances under which the Model S cuts back current? Any suggestions on how to diagnose this issue? How can I be sure that the problem is in the Blink so that if I replace it the problem will go away?