I ran into the same thing with my FBV3. I preordered one to use with my Firehawk 1500 and hardly used it and went to pair it up with my Pro Pro X HD and the pedal would switch modes but couldn't get any expression function with either the volume or the Wah. I took the pedal board apart and noticed the D1 had no light on it. I was going to replace the LED on the board but I talked to Line 6 this morning and got a part number for the entire board as it would be much easier to replace the board than to solder a new LED on the board. Waiting for a call back from full compass as to pricing but I will update when I get that info and decide what I am going to do.