I had some water enter my viewfinder/diopter (Oregon) and before it dried, I tried cleaning it too hard resulting in a nice blurry patch in the center of my viewfinder lens. BE WARNED to clean those VERY GENTLY.
Anyway after reading some other posts and courtesy of Owen sending me a replacement viewfinder, it was a rather simple fix. Owen previously posted that he paid $12 for a replacement from Pentax - let me know if anyone orders one and what the part number might be. Here's the
original thread with an exploded parts diagram.
The fix: (this was for my spare istDL but imagine others should be similar.
Remove 7 screws - Two under the popup flash, two beside the viewfinder. The outermost one inside the battery compartment, one below the dial on the left side of camera (viewed from back) and one below the neck strap tab on the right.
The screws are of various sizes, keep note of which goes where.
The top of the camera will now lift off, but is still attached by wires and ribbons: see picture below. The view finder assembly is probably removable, but the outermost lens is easily changed without that step. The outer piece of black plastic is held on with double sided tape, pry this cover gently off. (This is already removed in the camera picture, see pic of separate pieces below) Then there are four clips that hold the outermost viewfinder lens in, gently undo those four clips, the old will slid out, pop in the new one, and put it back together.
thanks to Owen..
Rick