Help needed diagnosing light leak

Hiya, I took my new Soligor TM (rebadged Miranda Sensomat with M42 mount) and 50mm f/1.4 Takumar out for a test this weekend with some expired film and had generally good results.

However, two shots had some sort of light leak that I'm unable to work out. Here are some details:

• The two shots were taken in different light, at different shutter speeds/aperture.
• The two shots were one after the other on the roll, with no leaks elsewhere.
• The leak does not extend to the sprockets, or even beyond the frame (see photos )
• The leak does extend slightly into the space between frames, but not all the way across.
• The leak has the same shape on both frames.
• I was using 30 year old expired film, but have had no problems on rolls from the same batch.

I'm stumped. My changing bag and developing tank are both light tight, I developed a couple of rolls after this one with no problems.

Any ideas?

Humm, 35mm camera question in the medium format fourm.
Common light leak points, ISO window in the back, back light seals especially the hinge and latch, viewfinder eyepiece.
Lay the effected negatives on the film plane as they would be when exposing the film and see what lines up.

FWIW, this looks to me that it could also be internal flare.

Since this roll was 30 years old and all other rolls came out just fine, personally I would suspect the old film rather than the camera.