My right rear airbag will not lift to proper ride height even when I have full 120#s air pressure. If I raise the coach with the leveling jacks the air bag will inflate and stay up. There is not a leak in the air bag. The coach will ride with all bags proper when driving. Is there a control arm or ride height devise I should be looking for.??? I heard you should replace airbags at 10 years. What is your advise.??