To get a neutral white balance in the mixed shop lighting I used the Custom White Balance provision on my Fujifilm X-T10 camera to reset it in one go. Lots of cameras have this same feature - you point the lens at a plain white surface that is illuminated like your subject and the camera measures the colour temperature with one shot. If you say OK to the result you have a steady basis to shoot from, colour-wise.
Only trouble is when I shot I had a real spot - obviously my sensor had picked up a lugie the size of a Volkswagen and when I stopped down to f:14 it showed up something terrible. Well, I opened the lens a little, put on flash, and resigned myself to cloning it out in the finished products - I didn't have time to wait for a sensor clean.
That's the three choices you have; clean, clone or claggy pictures.
After I got home I decided to see if I could clean the sensor myself with a puff of air - I wouldn't touch the filter in front of a sensor with anything else - I leave that to the staff at Camera Electronic when it gets really bad - but figured a puff from a blower would be fairly safe. As the spot was in the upper left of the picture the offending dirt must have been in the lower right area - I puffed carefully all round the place and then took another diagnostic picture of a clear blue sky and small aperture.
The spot. Sitting there. One puff and it was gone, and with the last photo....voila:
The answer, as Ernest our technician says, is to take as much care with the element surfaces as you are urged to do with the sensor - and to make sure that you are not re-contaminating everything