Sorry to bump this over one year thread but there is very little info on the Shimano 3SC hub.

This site has some very useful info on bearing adjustment but there must be different models because mine is a bit different. I have Green's book on old 333 hub overhaul but it is very different.

http://www.lafn.org/~dave/trans/bicycle/shimano3sc.html

Anyway, I got a bike with this hub and I really liked it. It is a bit rough spinning even after solvent flush/oil so I took it apart last night. What I found was a deformed bearing cage as posted above. It has 16 ball bearings in it.

One ball bearing was already out of the cage and a couple cannot rotate freely.

I am trying to find one like this before I attempt loose balls.

The 3SC uses two of these large bearing cages and another smaller one fo the sprocket.

Most non-coaster brake bubs use one large cage and two small cages.