It would have been relatively easy to check the sensor before leaving the shop by taking a photo of a light coloured blank wall or the clear sky and checking it at high magnification on the LCD screen, if that was my sensor I would be demanding my money back as it is worse than before. The copper hill kit is relatively cheap and easy to use, I have used mine about a dozen times over the last couple of years and have always been happy with the results.

Quote Originally Posted by jupiter618 View Post
carefully applied a drop of pure ethanol to the middle of the sensor;
This would be a very dangerous method in my opinion as if too much ethalol was used some could get into the mirror and shutter mechanism and remove the small but vital lubricant for those moving parts.
Keith.