I was mistaken...
Back on August 31, I wrote about the perils of not paying attention. Seems I was mistaken that I wasn't paying attention.
Nope, I wasn't doing the needed maintenance and such on the camera. All those spots in the picture were on the sensor (more accurately the sensor's filter), and were only really visible depending on the camera's settings. I discovered this was the case when I photographed the ruins of the Mosheim School, a relatively popular place to photograph west of Valley View, TX last week.
So, Saturday the 26th I ordered the stuff (Photosol.com Sensor Swabs and Eclipse solution) to clean the sensor. Watching the video, and doing the research on line (some good advice from ByThom), it looked like a piece of cake. And ultimately it wasn't hard, I just had to do it 9 times to get the sensor clean.
Once you get the method down, it takes all of 30 seconds to clean the sensor after a minute or so of prep. The hardest part is getting up the nerve to do it.