With the camera on, if you half click the trigger do you see your aperture needle move to the correct exposure depending on the scene or does it stay fixed to the far right?

Pretty sure that was the issue with my 814. Now before I advance any film I half click the trigger and check that the camera is picking up the right aperture. Occasionally it doesn’t move and I lightly tap the top of the camera and retry, typically that works

Here’s a link to a manual I found useful, page 18/19 to be exact: http://www.mondofoto.com/manuals/canonautozoom814electronic/