Thanks for your input guys. I am pretty sure the air cells have never been changed in the 21 years life of the car. I think I will replace them, then I want to flush and bleed the system. I assume in changing the air cells, there will be a loss of hydraulic fluid. How do I go about replacing the air cells, then flushing and bleeding the system with new fluid. I am aware that it holds something like 3.5 liters of fluid. One mechanic told me that just replacing the fluid is adequate, and that the system will bleed itself out by driving the car. Another advises a quick feed and bleed approach, where one person puts fluid in with the car running, and an assistant bouncing the rear of the car to operate the suspension. Your thoughts would be appreciated.