caution with the above advice, i once had a disco that had pulled the rear output bearing out of the transfer case because the rear prop was seized, so i wouldnt advise the above, just in case.
however.
remove the prop and pull away the plstic 'nut' and the rubber seal, and get some plusgas/wd40/ in there
if the prop is out, then bang it on the floor pile driver style to knock the short end in.
then get a lump hammer and **** the shaft yoke to knock the short end out again. this will takes many hours, sometimes even days of constant hammering. advise your neighbours to go on holiday.
eventually itr will start moving.
keep lubing/pile driving/hammering until it moves enough to pull the short end right out.
NB htere are 2 lines marked on the prop to show which way the sort end fits into the prop, it has to remain in the plane. if you cant find them, makie your own so that you fit it back together the same way.
pull the short end out and inspect the Rislan coating (thats the celar plastic)
if its all won out and split, your prop is best part o' shagged. replace ideally.
if it looks good and in one piece, wd40 the internal splines in the shaft and wire brush in there to clean the splines, and grease up/clean/regrease the splines on the short end.
fit it back together and it 'should' be like a wizard's sleeve.
cheers