I had my solinoids replaced u dear warranty. It still drifted. They sent me a new cylinder to install. As I was loosening up the hose to the cylinder, a large amount of art escaped. I just tightened it back up. Problem solved. The system is supposed to be self purging. It is for the jacks, but the slide cylinders are on the side and the port is on the side so almost impossible to remove all the ar from the slide cylinders. Also they don't fully extend or retract so there will be trapped air unless you unbolt the cylinder and hold one end lower than the other and fully retract and extend it a few times.