Hi,
My input. Hope it'll help.
Some absorbers are gas filled. You will not see any leakages coz it's gas.
If it's oil filled, then leakage diagnostic is the logical thing to see.
Reccomend action is to change the absorber since from your write up I assume the absorber have been used quite a while.... Don't resort to spring change first as I've made the same mistake with my Satria GTi...
Good luck. Let us know after you've managed to resolve the issue yeah?
Rgds