[Leica] Infra-red film and M6

["Russell Fox" <rsfox@armour.softnet.co.uk>]

During a recent visit to Kampuchea I tried a couple of rolls of the Kodak
infra-red film
in a 6 months old M6.
I was aware of the precautions necessary with this film and loaded /
unloaded in
total darkness e.t.c.
Following development both films exhibited fogging along the top edge.
Not a continuous line, but small dark fingers extending from the top margin

into the frame for about 3mm.
This occurred on most frames to some degree, in every case the fogging
lined
up with the band of film between the sprocket holes.
Some frames are O.K. mostly the shots taken whilst standing in shady areas
around an old Khamer temple.
I'm tempted to think that the seal to the hinge side of the camera back
may
be at fault, I’m told that infra-red light can beat many seemingly perfect
light seals
but I would hope that the M6 would be O.K. without the use of black tape!
Has anyone experience with Kodak I.R. film in Leica rangefinder cameras?
Should I have the camera checked?
All is not lost, some shots are fine and a few more will still be more
than
useable with enlargement and cropping but before I try again I'd like to
know
what caused the problem.

Regards
Russell Fox  (U.K.)