The "jerkiness" occurs exactly SIX times for every crank of the
handle.
I have not seen the inside of a Calyx, but if its construction is similar to
the Curado, Citica, Chronarch or Calcutta, then finding the problem should not
be too hard.
The jerkiness does not sound like a main drive, pinion, or levelwind gears, but
more like the worm gear or levelwind pawl. These are the parts that go back
and forth and lay the line on the spool. The levelwind pawl can "hang up" in
the worm gear if everything does not fit correctly and cause a jerk in the
retrieve. The cap over the pawl may be loose, there may be a missing spacer
under the cap (an optional piece in most Shimano reels...depends on factory fit
when assembly is done) or you may just have a bad worm gear or levelwind pawl.
Since it is new, I would take it back and exchange it. Otherwise, send it back
to Shimano and they will fix/replace it.
Brad Coovert
2003 Angler of the Year, Greenfield Bassmasters
http://www.greenfieldbassmasters.com