Outer Limits 4x4 Board

Hello everyone - First time user. Can anyone tell me the likely cause/likely fix for a leak coming from the point where the blue air supply hose enters the front diff housing on my troopy. ARB Locker fitted 3 years ago by ARB was working well a week ago, but on last attempt the compressor kept running. Checked at home - new diffoil on sump and around diff housing inlet area. The anti crimp springs on air line are in place and there appears to be a threaded section about 20mm long entering the diff.

Cheers
Chris

Engage locker and brush on some soap/water.
Will bubble from where the leak is