Sorry I do remember seeing your email now, I was heading out at the time and then completely forgot about it.
Try this way select the arm all the components, group them, delete the history. Select duplicate special and set the scale to -1 in all three axis. I've just tried this on your file and it works on 2016.
If you still have problems let me know in this thread and i'll send you the file.
Sorry about not getting back to you i simply forgot.
All the best
From a readers' Q and A column in TV GUIDE: "If we get involved in a nuclear war, would the electromagnetic pulses from exploding bombs damage my videotapes?"