Dave 2000
Not all Land Rovers are useless!
I cannot read the whole thread properly so it may have been mentioned? Spring height when out of the vehicle has no relation to spring tension whatsoever assuming they are the same, it could simply be a bad spring that was cut wrong, missed or went through the annealing/hardening process? Assuming all else has been tried and flicking through the above it seems it has, then I would change the springs for a new set.
Regards
Dave
Regards
Dave