On my desk there is lens that is critically ill, a non-AI Nikkor 1.4/50mm. This is not an expensive lens these days, but I fell pity with it. It suffers from cleaning marks, and it's somewhat blotchy. It does not look so bad, but there is a problem, and it does affect contrast on the images. I know this can't be fixed, but are there any dirty tricks to make it work better? What is the best way to clean the front lens if a first try with a lenspen fails to remove the 'blotchyness'?