Originally posted by clackers one crude estimate for the overall failure rate would be only three percent.
Hey, I took a stats course once and you can only make that estimate if there is a high probability that 100% of the 90% who didn't answer the poll have
not had anything resembling an aperture block problem with their K30/50. But you can definitely estimate that the actual failure rate is significantly less than 30%, because a) other failures will be perceived as being related and b) internet polls, regardless of how well they are implemented, have a high probability of getting responses that don't accurately reflect the entire population.
What can be said, regardless of the actual failure rate, is that the probability of having this exact failure in the future goes down dramatically over time. Mechanical things don't fail at random, it only looks that way because we don't know what caused the failure to occur when it did. Even when there is a known faulty design or manufacturing defect, it is not a sure thing that every single example will fail, because in every instance there is something external to the component itself that causes the failure (otherwise it would fail immediately and leave the population of potential failures). As that component is operated over time without failing, the probability that this particular component will not be exposed to external agents of failure often enough to cause its eventual failure goes up. Unfortunately, there are many components in a camera that can fail, and if the camera is operated enough times to cause some component to fail, the camera will become inoperable, regardless. So, if the buyer of a used K-30 or K-50 operates it several times without failure after receiving it, the probability that camera will fail from something other than aperture block is much higher than 80% (assuming an actual aperture block failure rate of 20% for all K-30's and K-50's produced). I have no idea what my early build K-30 with only 13,000 shutter actuations and no failures of any type, is worth in the used marketplace, but I expect that it's resale value is low enough that someone could take a chance on buying it from me with minimal risk.
Additional verbiage: In another life I was a warranty administrator and worked in owner relations for Ford Motor Company. Every purchase comes with risk, risk of not satisfying the needs of the buyer at some point in time. Even if the unhappy buyer returns the purchased item for a full refund, there is a cost to the buyer of not obtaining all of the satisfaction he or she paid for. Even if the purchased item provides wonderful service for much longer than expected, there is the risk that whatever is purchased to replace that item will provide much less satisfaction. No matter how you look at it, buying things results in unhappiness.