Air nailer repair help

I dropped my framing nailer and now there is an air leak. It still shoots nails ok but there is a small internal leak of air that is causing the compressor to run fulltime to keep up with the leak and using it. Any ideas and what to look for before I open it up? It is a chicago pneumatic 21 degeree framing nailer.
Thanks in advance Tom
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.