The freewheel takes a 4-prong SunTour removal tool ... I'm starting to think that getting this thing apart is more trouble than it's worth...
Those old SunTour freewheels were notorious for seizing solidly on the hub, just as you describe. A new wheelset with a modern cassette hub will be a good upgrade.
-- "Bicycling is a healthy and manly pursuit with much to recommend it, and, unlike other foolish crazes, it has not died out." -- The Daily Telegraph (1877)
