The one old HPLC system contents of piston pump and damper as a separate units. Amperometric detector is used. In begining, damper (SSI) has reduced pulsation effectively. Some time after pulsation has been increased again while the pressure level (fluctuation) seems to be unchanged. Does only damper damage may explain increased pulsation or another reasons exist?

How about malfunctioning pump valves? How about a leaking piston seal? How about improperly degassed mobile phase? How about improper purge or priming?