I have several services with a geodatabase feature class having attachments. These attachments are almost always PDFs. After much experimenting I have noticed that any PDF over 5MB in size will load as gibberish in the browser window.
To narrow this down to ArcGIS server, I put the same file out in a directory on the web server and browsed to it and it opened fine in the browser using the Acrobat plugin. Previous web searches had led me to believe there might be a problem with the plugin, but since it displays fine outside of a ArcGIS map service I believe the plugin and the web server (Tomcat) are configured correctly.
Is there some minimum size limit or buffer size in the REST configuration I need to enlarge? Because it seems to always be around 5MB I get the impression there is some coded limitation somewhere that needs to be increased.