I have several Riteway film holders that all work fine, but my lone Fidelity Deluxe film holder won’t close when there is Shanghai 4×5 film in it. When film is inserted it the flap won’t close properly because it’s too long for the holder. Because of this, the dark slides won’t go in all of the way. I don’t know if it’s a design flaw, or it was missed in QA.
Anyway to fix it you’d need to trim the inside frame to allow the flap to close fully instead of sitting on top of the film.
As you can see, the film doesn’t fully fit, and it sits slightly on top of the frame. Just enough to prevent it from closing properly.
The solution was to use the film as a guide for the size, and trim the plastic enough to allow the film to fit.
Once trimmed the film fits, and the flap goes down all of the way.
After that, I gave it a coat of paint, and it works properly. Flap closes and dark slides shut completely.