Assuming nothing is damaged, the only resistance should come from that created by the Thrust nut, and that created by the steel indexing ball.
The ball may be gumed up with powder and other residue preventing free movement.
When I get a new machine I always do a complete disassembly and do a through cleaning. Remove the brass "steel ball plug" from the bottom of the machine, remove the spring and ball, and clean those parts so that the ball moves freely in its hole. When you reassemble the machine and tighten the thrust nut, it should not be tightened to the point where it impedes movement of the shell plate. It should only be tightened to where all but eliminates the rocking of the shell plate cause by the pressure from the steel ball.
I always use a little grease on the inside of the shell plate where it contacts the column shaft, and on the underside of the thrust nut.
