I've never heard of adding Seafoam. Lippert recommends removing a quart of fluid from the reservoir and adding a quart of motorcycle fork oil or Caterpillar hydraulic oil additive.
Usually this is for popping on extended jacks.
A couple of my jacks will drift down over a period of time but the system will raise them as soon as the ignition is switched on.
A link to recommended oils that might help.
https://manuals.heartlandowners.org/...%20Systems.pdf