My P200 has a mark on one of the inner lenses. An example of the smudge marks is here (above the green house). The smudge appears in every photo in the same spot. I did some stuff on my own, but the smudge remains. Is there anything else I can do?
That linked PDF looks thorough, and pretty cool!
If you followed the instructions, and you managed to clean the glass elements accessible to you, the next step is to disassemble the zoom lens assembly and clean the elements inside.
Whether this is possible, or even if it's a good idea, is up to you.
The P200 looks like a nice camera, but it was introduced 6 years ago according to DPreview. Unfortunately many compact point-and-shoots are built for economy, not robustness. You may have to conclude that trying to fix this issue isn't worth it.