http://home.online.no/~arban/Pics/FE3-HLA.jpg
the inner most region above the red stripes is what needs to be full of oil for them to be hard.
it doesnt matter so much that it is hard before you put it in, rather that it has the capability to become hard.
so long as the small ball and seat are perfectly clean and the rest of it is clean enough, then it will function well.
see the first page of this thread for a description of how to fill them with oil if you want to ensure that your cleaning was good enough before installation.
fred.