Originally Posted by sixpax

...loosen the bottom collar of the two that are up top...loosen the only one at the bottom. Use a strap wrench and turn it the appropriate direction. Can do by hand but is fairly hard to turn. If you do it correctly, the strut is not rotating at all, just the fine threaded internal piece is moving up or down inside the strut.

Can do it easily by hand without a strap wrench if you take the load off ... so another jack to compress the spring perch.