Clevis
Hey evilmonkey. Good advice here so far.
I hope I understand what you are trying to do.
Assuming no spring compressors, or that you have 4 arms,,,do you have a spare hydraulic jack (it wud have to be a porta-power - I'm guessing not) -nip up just enough to creating some friction then create a little directional movement with a decent bar, directionally TAPPING the collar/sheath radially and directionally with a SOFT FACED hammer and if it moves to where you want nip up further. A block of wood tapped on the end grain with a ball-pein hammer in the direction of travel (be VERY CAREFUL)not to marr the surfaces by misdirected hammer blows of any kind......and it is not a steam engine so don't flog it like you would with a flogging spanner (oops showing a bit of age there).
Tuffnol, aluminium, or brass dollies could also be used but be very careful not to marr any of the surfaces.
Remember to push from either side a tiny bit at a time....push, tap, go to opposite side, push , tap and so on. Keep it even.
Please have the vehicle adequately supported.....on rated stands.
Mark (with a graphite based pencil or felt marker your starting point) I don't suggest centre popped reference marks here....also clean well with a wire brush or whatever you can.
I'm NOT suggesting lubricant as you are relying primarily on a tightened collar to provide friction to locate.
Sorry this is hard a technique to describe in writing. Please pay head to the notes about marring surfaces....brutalising is not the answer...finnessing is.
Best of luck
This is a bit like a trail fix.
I wish you well. It is doable but this is the tuff way round.
Please let us know how you get on.
Cheers
Auberon