Quote Originally Posted by david b
For me, the first thing i do is set the lens on B and then shine a flash light through it. This is normally a good way to see how things look.
After this look at the both the front and back elements with the light coming at a 45 degree angle so you can see the color of the coating. This way you can see any imperfections in the coating. You should see an even color over the entire element if everything is OK.

Look for any lubricant on the aperture diaphram blades.