[fstop18]

This may sound weird, but I happen to notice that if you gently shake your camera near your ear, you may hear a sound of something sliding back & forth: maybe this is the troubled aperature thing moving. If it moves that would be good; maybe you can do this once in a while to help clean the contact point to lessen failure(?). I've done this sound test on 2 K-50's and both sounded the same. I've done this to a K-3 and no sound. All cams were around 2K shutter count. You don't really shake it, just throw your arm back like throwing a football, with the lens forward and carefully listen (that's the way I did it). I'm not a tech, but thought this would be interesting. thanks

[Not a Number]

What you are hearing is most likely the sensor block which moves somewhat freely when Shake Reduction is powered down.

[Giklab]

This ^

[MarkJerling]

Read more here - See number 8. 15 Beginner FAQ's for Pentax DSLR Users - Articles and Tips | PentaxForums.com

[IgorZ]

I have a sliding sound in my K5 and was always wondering what it was

[VoiceOfReason]

Talked a friend into getting a K1 and he told me he though his was broken after getting it. I got a chuckle out of that then told him what it really was.

[ekip]

There is another sound you get from the 2 hinged lifter arms inside the flash unit. If you pop the flash up they are extended and dont make noise any more.