[Leica] Flakes in lens

[Charles Babington <cbabing3@swbell.net>]

I have just received a used 50/1.4 Summilux-M from one of the well known
vendors of Leica equipment.  It is very clean externally, focus and
aperture rings work smoothly and are not loose, the glass surfaces are
scratch free, and the price is good (compared to other offerings in this
month's Shutterbug.)  However, there is a large black "furch" inside, at
about 4 o'clock (looking from the front), behind the diaphragm (I would
guess it's on the lens surface immediately behind, judging from the lens
diagram on the box.)  It appears to be about 1/8 inch long and much
narrower than that, but wider than several hairs.  It could be a bit of
paint.  Rapping the side of the lens with a knuckle (not hard enough to
hurt me) doesn't move it.  There are a few other rather tiny black spots
around the edge of the glass, and the usual bits of dust, but I'm not
worried about them.

The thing is close enough to the edge of the element that if you close
the diaphragm down below f/2 you cannot see it silhouetted against the
open back or front of the lens (no matter what angle you look in from.) 
I will try to shoot a roll tomorrow to see if there is any visible
effect on film, but I'm wondering if I may safely assume that effects
would only be visible on film at apertures where the item is visibly (to
the eye) in the path of some light ray coming through the lens?  If so,
I only need to check the largest couple of aperture positions.

TIA for anyone's experience here.

Cheers,
Kip Babington