Electrically, everything on my works fine - I've seen older "normal" remotes where often used buttons develop a kind of numbness and you need to push them harder to execute the button's function. Never had this with any of my Prontos, though.
Anyway, that's not the issue here. I just noticed that the controller ring does not turn as easy as one might like. When only pressing on it lightly while turning, my finger slips over the surface even though the ring has this 3D shape to increase the grip. To me it feels like there might be some grease/dust inside the controller assembly. It does seem to develop a little less friction when operating the ring constantly for a short while.
When cleaning the spaces next to the ring with isopropyl alcohol, it seems that the moisture lubricates the controller ring and I can rotate it very easily. Of course, the alcohol evaporates after a few minutes max and we're back to start ;) I'm not sure if applying some drops of silicone oil into the gaps would do more harm than good.
I'm a little hesitant to disassemble the whole unit. For one, there's no service manual (at least not that I'm aware of) and I don't want to risk damaging the device. I also haven't been using the rotary controller much, so this isn't a big problem for now.
