Hi, it could be light leaking between the metal caps on the shutter blinds - you need to place the film in the camera upside down with the emulsion facing the lens to work out the exact place, then wind the shutter with a torch shining into the lens throat in a dark room to see if you can see light leaking past the capped shutter. It is tricky to fix. It also looks like you are getting some light leaking in on the edge of the film? Again hard to detect/fix but could be deterioration of the light seal between the camera body (which slides off the chassis once the various screws and self-timer handle + lens mount are removed.
Cheers,
Steve