I have 2 388's and new JR11x, and a few JR 2.4 systems in between and I can tell you there are things I could do on the 388 that can't be set up the same on the newer stuff to make it work the same with older stuff. It is why I traded up and up to the 11x trying to make a program mix to mimic accel mix for rudder offset based on how fast the throttle stick is moved, no go, even horizon techs could not come up with a way to simulate the mix and told me it was time to throw my old JR gyros out and step up to new ones. I don't like heading hold and stuff on scale birds, the tail needs to be a little loose IMO to look scale/smooth like in flight and the scale like reactions that heppen with older slower gyros coming in and out of a hover and in turns and such.The battery back up is a special battery with tabs welded to it, I have a couple but changing them with out lossing the running program can screw them up to where it has to go back to a service center to flash the program back into them. This happened to me with upgrading the radio to be able to do 4 servo CCPM mixing, if back up battery is removed with out keeping at least 2.5 volts present the radio reverted back to the standard set up but still at least talked to the rcvr. If it was stone dead for that long that could be the issue, maybe the main program became corrupt but it sounds like a issue beyond such.I know its hard to let go of stuff some time, my 388's are from 1990 and both look better then some friends radios that are only 2 years old and I seem to fly smoother with them then my newer stuff but if the radio has an issue it is going to cost you more to fix it then it is worth unless your really really connected to it, and then you may even find Horizon doe snot have the parts to even repair it any more, those older chips are just not aroound any more with ROHOS implemented now.