Mason- It sounds like you have an air leak. The compressor is constantly cycling on and off becasue its presurizing the entire axle, forcing the gear oil that sloshes up through the diff breather.
Turn on the compressor and time how long it takes to cycle on and off. I believe ARB says 14 min between each cycle after engagement. Mine off road is very random, but for the most part does not cycle for up to two hours with both Diffs locked.
My rear ARB leaked when I first got it, Marlins Crew made VERY clear that ABSOLULTELY nothing can be touching that copper air line on the lower left hand side of the diff during install. If it even touches the housing, it will thingy the air colar and cause a leak. This unfourtunately took me 4 tries before it stoped leaking, you simply route the copper line as close as possble to the third member. If it touched the housing in any way, even slightly, it will leak.
Apparent ARB changed there design from bolts holding in the shift collar to none at all, and I was assured this is a far more reliable design.
Good luck! I know it can be frustrating to have a $700 doorstop spinning pointlessly in your diff.
sAs for the it not disengaging, well shoot I have no idea
Im assuming its a spring that helps return the diff to open. One of the last gadgets on my truck I wish I understood better.
