Often hammering repeatedly works along with heat. Can you put any heat on it?
Also, since it is going to be replaced, put the nut back on and bring it up even with the end of threaded portion and whack on it there as well.
Regarding the steering damper and whether it needs replacement, take one end off and see how easily it moves in and out. It should resist well and not skip or have any air sounds in it.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)