ar636

I have a plane that I've flown for several years, always without ANY problem at all. It was a BNF with the AR636 RX, AS3X and SAFE. All of a sudden it just lost its SAFE functionality. I've tried re-binding (several times, actually) and it binds OK but WITHOUT SAFE. Do these RX deteriorate...

I am trying to find a good and thorough explanation of "gain." I've asked Horizon and they more or less said they don't have anything. I'll take a video or a written explanation, etc. FYI, I use ar636 RX and a DX8 RX.