Either pull them out with a deep socket, and a length of threaded bar or, my personal favorite... burn them out with a blow torch... a bit stinky, so do it outside... heat up the central tube until you can push it out with a screw driver, then let it cool, and cut the rubber out with a hacksaw, then split the metal sleeve with a hacksaw either way is labor intensive...
I wanted to replace everything which is rubber that I can as the van is completely stripped down to a shell and a pile of parts but, maybe if they won't come out they are ok and just need a clean and some graphite powder you may be dissapointed in a years time when most of the new rubber has perished and split, if the original stuff is still in good order, clean it and leave it in place
