Porter Cable C2550 Manuel D'instructions page 24

PROBLEM
Knocking Noise. Possible defect in safety
Squealing
sound.
D28093
CAUSE
valve.
Defective check valve.
Compressor mounting
screws loose
Carbon build-up in pump
Compressor pump has no
oil.
Operate safety valve manually
by pulling on ring. If valve still
leaks, it should be replaced.
Contact a Trained Service
Technician.
Tighten mounting screws,see
Parts manual for torque
specifications.
Have checked by a Trained
Service Technician.
See Oil-Checking paragraph in
the Maintenance section.
24- ENG
CORRECTION