Shutter oil slick on back of front lens element?

[George Hart]

My Schneider 75/5.6 lens accumulates a fine, thin slick of oil (~6 x 1 mm) on the rear lens surface of the front lens element. It's curved, shaped a bit like the Nike symbol, and it wipes off easily. Fire the shutter and it's back again, in exactly the same place. The shutter blades are clean and free of obvious oil or lubricant. The front lens surface of the rear element remains clean. Whether it affects my photographs I can't tell, because I can't take a shot without the oil slick appearing, but my pics are uniformly sharp etc, so I guess that it may not affect image quality very much. But none of my other lenses has this problem, and I would rather not have the potential for images to be affected. Has anyone else experienced this, and what (other than stripping down the shutter) can be done about it? The lens was first purchased ~8 years ago.

[patrickjames]

Your best bet would be to have it serviced, which neither costs much nor takes a lot of time. Otherwise you could just flush it with Ronsonol and let it dry out.

[GPS]

Take the lens out of the shutter and fire the shutter over a piece of paper as many times as you have patience for or as the oil shoots on the paper, whatever ends first... Like that you can take most of the offending oil out perhaps up to the moment that it will not shoot it any more. Primitive but cheap and acceptable in emergency.

[George Hart]

Thank you for your suggestions!

[John Koehrer]

It's liquidized grease, probably on the blade operating ring or blade housing. You may be able to cure it yourself by flush cleaning the shutter.
Remove F&R lenses & use a drop or two of Naptha applied to the blades & repeatedly operate the shutter, repeat this two or three times & it should get the remainder out of there.

[George Hart]

John's method worked. I used a very small amount of absolute alcohol on the shutter blades. Many thanks.