I know they should be treated to a good clean every once in a while to keep the minute movements of the linkage moving, but should the springs need retensioning/replacing as no doubt if the manual height control lever is kept at either service high or low when parked, there is a constant pressure on one of the springs that side, and if the car sinks there will be a constant pressure on the roll bar/plastic link spring
The reason this got me thinking is that couldn't this have an adverse affect on the ride height?