I'm presently doing an oil change on the rear shock on a 1996 XR600R. Have done several oil changes on previous Hondas and never had this problem before. I have the shock upside down in vise, fill reservoir to within and inch of top, install bladder, add air to bladder, and then fill body to within and inch of top and install shaft. I can push the shaft in ok, but when I proceed to pull it out to bleed it will not pull out. I checked the rebound valve at top of shaft and it seems to be free. Shock worked before attempting to change oil. Any help would be most appreciated.