1. Do you have the PSI gauge? (I replaced 2, on my 3rd now)
2. If so, bypass it & get a spray bottle of windex or soapy water.
3. Run a direct single line from pump straight to shock(s) & see if it maintains air PSI.
4. Spray system to re-test for leaks.
If it's a Legend Air Suspension, they have a lifetime warranty on all their products.
Look them up on the web or give them a call, they provide great customer service.
They can rebuild or upgrade if needed. 1-605-720-4202 Sturgis, SD