For several years I have been struggling with getting air in my steering system. It also was also squealing badly. After bleeding the system many times, which only lasted a couple trips, before the the steering started slipping again. I finally had a tech come out and check out the system. Turns out the seals in the helm were bad and the system hydraulic fluid was fouled. Had a new helm installed. And oh by the way the old one was made of plastic, the new replacement is metal! We also had to flush my hydraulic system and add new fluid. The difference is amazing.