I was setting up my rig to help teach a class this evening and when I turned the air on for my DIN mk 25 eco it started making a droning honk noise. To rule out hose and oring extrusion I turned the air off and checked the hoses for both security and for issues with the orings and found no issues. I am assuming that there is an internal issue but there is no free flow. Any ideas about what might cause this?