Just reviving this thread to say that my XE-1 (European version of XE-7) also had a film wind lever which would not always return by itself. It would also sometimes jam up if I tried to advance quickly after pressing the shutter, although it was always o.k. after releasing pressure and trying again.
I removed the screw (top bit with two tiny holes) and took off the lever mechanism (remember the order in which the parts came off!) and sprayed on a very tiny amount of Servisol contact cleaner. This is sold as a switch cleaning lubricant so I assume I will not need to add any lubricant later (although if I do, it's not a problem).
The wind on lever is now as silky smooth as it was when I bought the camera.