I'm taking over a web app that allows users to view PDFs from Map Image Layers. There is a possible server location in the data, but it is either not accessible from my current machine or no longer active. IT hasn't been able to track it down either, which makes me believe it is no longer a real location.
I've had the thought that these images may be stored on the ArcGIS Online server but I can't seem to track them down anywhere. We do use a feature layer for one of our datasets and I have been able to find the image files that it uses.
All of the links in the actual online map work, so I know they're being stored somewhere. Where else should I look?
Table in ArcGIS;

URL structure of attachment https://oursite/arcgis/rest/services/SP/SitePlans/MapServer/0/93430/attachments/398
Thank you