Originally posted by dave216 dirty contacts on gear (9) seen at pictures 3 and 4 above cause mirror flop issue on k10d, so i think there must be similar mechanism in k5
Maybe dave is onto something. I dont see it being *directly* related to the batteries or voltages; follow me...
Perhaps the issue develops like this: Heat causes the grease to liquify to a degree, or at least alter its viscosity. It then starts to flow a little and ends up smudging across the brush contacts etc as seen on Gear (9).
Maybe the grease they use they've changed due to RoHS etc.. and the new one changes its dielectric (??) properties when its changes it viscosity. Or maybe continued heat cycling causes it.. maybe the smaller body of the K-5 combined with the metal enclosure means they run hotter
New/Over voltage batteries initially cause the problem to exacerbate in one of two ways maybe - because they don't cause more voltage but will cause more heat dissipation in the regulators which heats the grease again mildly, again changing its viscosity. Or alternatively there is an issue with the regulation and the extra voltage is enough to arc (I doubt this...but possible - but i reckon its more just extra heat dumped via the regs which the circuit on my k20d has and can't imagine thats changed...)
The problem finally develops into an ongoing issue once the grease sufficiently covers the contacts. This is also why some people can 'short cut' to the 'goes nuts all the time' stage.. all depends where/how the grease ends up.
This could also be why some people are lucky enough to not have problems - Or maybe there was a period of time when the assembly line over greased some components - causing the sporadic appearance now.
of course.. I'm just guessing.... but also fits with why they changed that component when one got "repaired" in another thread (also referenced here somewhere...)