When Canon built the QL17 cameras, they often made adjustments to the meter by gluing a piece of gelatin neutral-density film behind the meter eye on the lens faceplate. Your camera may have had this bit of film installed, but as it is held in place with water-based glue, it may have fallen off. You can remove the lock ring around the face plate and see if there is a bit of filter film behind it. you can make your own replacement by gluing a piece of an old film negative behind the plastic eye on the lens nameplate. You can try different shades until you get a good reading.