I’M HAVING PROBLEMS WITH MY TRIM SYSTEM. WHEN I TRIED LOWERING THE UNIT, IT STARTS TO SHAKE. I THINK THAT THERE IS AIR IN THE HYDRAULIC SYSTEM. I TRIED CYCLING THE SYSTEM UP AND DOWN A COUPLE OF TIMES TO BLEED THE AIR, BUT THE PROBLEM STILL PERSISTS. DOES ANYONE KNOW HOW TO BLEED THE HYDRAULIC...