Just to be sure you've understood.
The damage has now been done.
The electrical contacts have been oxidized to the point that any effect(like water, or lots of usage) make them more susceptible to
stop working again.
The last issue was that the added moisture made the contact more fragile(electrically, not mechanically).
So, even if you're careful now and don't allow moisture on the camera again, just the usage could cause it to
stop working again.
Think of it this way: water/moisture will follow a random path. if the moisture got in again and it only followed the path of the track, moisture being conductive to a certain degree, the dial will still work.
As long as the electrical path is maintained, the dial will work.
But as the moisture doesn't follow a set path, and will just go anywhere(ie. random) it most likely is shorting the contact path to ground(hence not working).
If the moisture happened to touch some other part, you may find that the dial may operate some other setting instead. (without knowing the layout of the insides, no way to tell what).
So the damage is done, the issue .. ie. real issue, is that the insides that allow the electrical signal to work have almost certainly been affected by oxidation/rust.
I'd still either:
1/. do the spray thing. The spray will clean off the oxidation. The Contact cleaner is fine for plastics, just don't know how it may affect the leatherette covering if there is any close by on the outside.
2/. take it to a service place to get them to open it up and clean it up.
Long term(hard to specify an exact time frame) .. leaving it is the worst thing to do.
I can't imagine that you'd sell such a camera in the next year or two, but assuming you don't, and you use it on a very regular basis, and use that dial "all the time" .. I'm quite sure that within two years it will
stop working.
So option 3/. would be if you could assign another dial to operate the most used variable, be that
shutter or
aperture or whatever.
Note too: my experience with this electrical issue is limited to some electronics gear, zero cameras tho, but more so auto electrical gear, switches and plugs and suchlike .. but they all operate in the same manner re the oxidation issue.
If you want to visualise what I'm referring too and how water ingress affects electronics, there's a guy on Youtube named Louis Rossman who does videos, mainly on repairing Apple hardware(he's actually very interesting, even if the topic itself isn't).
But, through many of his videos, a major theme is that when the gear comes in for repair, the customer insists that they haven't spilled anything on the gear, or got it wet or whatever.
This may have been true in an immediate sense, that the stuff stopped working, but they didn't spill any moisture compound on it.
But over time, say months or a year previously! ... they did!(almost always). But they thought nothing of it, and the oxidation slowly gets worse, till one day .. later ... the thing
stops.
Same happens in the auto world. Water is the worst car killer, and all cars nowadays are electronically controlled in more ways than what they should be. Such as park brake application!
That last one makes zero sense to me, that the park brake should be made electronically! But they are, and many are fitted low on the centre console, exactly where a spilled drink will randomly flow down too.
Clean up the console area and it appears that the spill has been dealt with.
But much later, the park brake no longer works because the switch got contaminated a long time back.
I'd love to meet the moron engineer that thought that the park brake needed to be made electronic, when for over a hundred years the 'ye olde worlde' cabled types worked perfectly for decades without any problem.
The added complication is that many of these electronic park brakes HAVE to work for the car to start, and if not, no start from the car! .. makes it even worse.
Anyhow ... just my advice .. don't leave it(too long).
Thanks useful information: 
Threadstarter
Originally Posted by arthurking83
Just to be sure you've understood.with...
Reply With Quote
