Have the loader show how they decide it's seated, from their actual working position. A camera-side photograph can hide the awkward part of the job. I'd include the reference plates rather than an empty holder demonstration.
Oliver, yes, ask that before accepting a helpful new stop right across the inspection area. And Hazel, keep the real defect example in the review so visibility isn't judged on a clean plate alone.
Could the loading orientation change instead? I don't know your space. It might be worth comparing before asking the loader to perform a more elaborate check at the same hidden contact.