I am making this up as I go, but how about the following? Load camera with film. Wind film on. Remove lens in regular room light. Let sit 10 minutes. Replace lens, with lens cap on. Fire two blank frames. Without re-cocking the shutter, remove the lens again. Let sit 10 minutes. Replace lens with lens cap on. Expose two blank frames. With lens and lenscap on, place camera in direct sun with the front of the camera facing the sunlight. Wait 10 minutes.
Rewind film. Develop. - you will see if there are any pinholes in the front curtain, the rear curtain and any light leaks from the front of the camera where all the holes (screws, castings, etc.) are.