I have been having a problem with flare coming from the film edges and really messing up my negatives when I use Iso 100 or 200 film. I have checked the various corners, joints, and doors for light leaks and it appears to be coming from the rear (backing paper side) rather than the front (emulsion side), hence the "leaking" onto the film from the edges. I suppose when these cameras were made, they were using 25 or 50 speed film and it wasn't such a problem.
One thing that might help is to replace the faded orange-ish film window with a darker red one, as the window is doubtless a significant light source. I might put a foam and/or black velvet "donut" around the window on the inside of the camera, making it thick enough to brush against the film just enough to keep the interior of the camera from filling up with light.
I would like to hear from others who have had this flare problem and how they have dealt with it.
By the way, I have some No. 2 Brownie box cameras that have the same problem, again with light getting onto the film from the edges, suggesting that the light is leaking from the rear of the camera, with the red/orange window being the usual suspect.