How do I remove the lens

I have a mark on the inside of the lens of my S9700. I almost looks like a chip, but I'm hoping not, and can't see how that could have occured. I know how to remove the outer most cover by twisting to the left with the lens extended, and can see that the lens glass itself is suspended by the rest of the structure. There are 3 screws which seem to be holding this assembly in place, but having removed them I still can't lift off the lens structure easily, and I don't want to force it too hard in case there is something more I have missed. Any help would be appreciated.