They should rotate with a little resistance when there's no weight on the wheels. If it doesn't it's because it's either siezed to the sliders or somebody has tightened the can between the rubbers, compressing them tightly. This restricts the fore and aft movement of the can and prevents it being effectively interconnected. When the front wheel hits a bump the can moves forward, pulling the rear spring and raising the back of the car. It prevents a fore and aft pitching motion.

Paul,
it may not be a _major_ issue, but it does mean that the suspension isn't working as it should, since the interlinking between front and rear axle movements will have been disabled and the ride will be less comfortable.

If it's one side only which has seized up, that's even worse, as the effective spring rates won't be the same on each side of the car...

ken

any luck sam? when i was messing around with my cans, i found that the wrong adjustment on the cans, ie too far forwards or aft, caused them not to rotate, so maybe undoing the 46mm nuts, and adjusting it so its central between the two tubular slots (same amount of gaps between doh nuts and tube thing if that make sense