I have hynautic steering & have rebuilt one of the helm
pumps. It has a oil
tank that is pressurized to supply the system. A friends boat
has a sea star system it has no separate oil
tank, the helm it's self holds the oil. Does your system sound like either one of these? May be able to offer some help with more info on what system you have, can't even order parts
if needed till you know what you have.