1
System leaks
CheckUltrasonic leak detector or soap on fittings. >10% loss = major.
FixRepair fittings, hoses, drains.
2
Worn intake filter
CheckVisual / differential pressure gauge.
FixReplace element.
3
Unloader valve stuck open
CheckAir bleeding from unloader during run cycle.
FixRebuild/replace unloader.
4
Worn rings / valves (reciprocating)
CheckPump-up time test vs new specs.
FixRebuild head / replace valve plates.
5
Inlet modulating valve not fully opening (screw)
CheckVisual; check pilot air signal.
FixService inlet valve, check control air solenoid.
6
Belt slipping
CheckVisual smoke/squeal; deflection test.
FixTension or replace belts and sheaves if worn.
Safety
Lockout/tagout before opening enclosures. Verify zero energy. Bleed system pressure before opening any pneumatic connection.