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Message: <blockquote data-quote="spb_stan" data-source="post: 627260" data-attributes="member: 43545">If it works some of the time, it is probably the very common problem with all switches, jack normalizing contacts, potentiometers and connectors: Exposure to atmospheric oxygen oxidizes metal surfaces and becomes an oxide of the metal, which is a very good insulator.All metal get is but the rubbing action and normal use usually prevents the moving contact surface from building up too thick a layer of metallic-oxide. It is not a bad thing, it protects the surface from deeper oxidation normally and is actually intentionally added to metals such as aluminium because it oxidizes rapidly after smelting. If cut into a bar of aluminium you see a bright shiny mirror like surface but the undisturbed surface it the normal dull gray "aluminium"color.  That is surface if coated with  aluminium-oxide. The same oxide that keeps plates of capacitors from conduction able to prevent hundreds of volts from conduction between the plates that are only a few micrometers thick.If the camera sat for a while there is a good bet it developed the problem while sitting and was not known to the owner before he shipped it.It is easy to fix, there are de-oxidizing chemicals which attract the oxygen more than the the metal does and wash it away. Most sprays labeled as Contact Cleaner are the worst thing possible for contacts, look for a de-oxidizer instead. Caig Laboratories makes a whole line of liquids and sprays used in the electronics industry to fix oxidized contacts. A 5% spray solution that is very effective is <a href="http://store.caig.com/s.nl/it.A/id.1982/.f?sc=2&category=188" target="_blank">DeoxIT #DN5S-6N</a>   There is a version without the N suffix that does not dry as fast which is best for moving contacts. But being inside a camera, I suggest the N version.  For those in Europe, Cramolin ContactClean is about the same, maybe better since they invented the chemical back in the 1960s and licensed it to  Caig Laboratories which was their US distributor at the time.IF this is the problem and if the wheel feels normal, smooth and sure on each detent, it most likely is, than getting a tiny bit inside the switch means pulling the side cover off and applying a little so it flows into the contact area. It is very thin and wets easily so you do not have to get inside the switch.  With the remainder, if you have any hi-fi gear with scratchy static  sounds from the speakers when turning the volume controls,or treble control this will fix it instantly.   If the switch feels odd, uneven when moving around the detents, it is probably the switch itself. Easy to replace but harder to get inside to replace it.</blockquote>

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