2003 w220 s500 air compressor

  mercedes/s-class/2000-2006

So I just bought this car was told air system will need replaced. I figured no problem I'll put the conversion with coilovers and call it a day. Here goes I started looking at car and did some simple once over stuff. I got soapy water sprayed bags/strurs while car was running with the compressor running I didn't see a single bubble as I was looking for some sign of wear nothing. I heard the compressor rattle a bit so I stuck my head down by bumper and it sounds like it's just blowing the air into atmosphere. I hear puffs of air clearly. So could it be a line broken either at compressor or tank? It would be cost effective to fix that rather than buy struts if this is common issue with these I'd take the time to remove bumper cover and repair or is what I'm hearing somthing totally different? I build custom vehicles and have installed countless air ride systems so I have experience with air struts and bags but zero experience with w220 airmatic. I'm sure that there is experts on this especially after seeing so many people talking about issues with the system... So anything to help aid my decision I will appreciate greatly.

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