while you will want to follow Rick's advice if you can get into a REI store to personally inspect the poles, for those who cannot do so, perhaps my personal first-hand experience may prove helpful.
i've run into this problem many times with my first trekking poles (Komperdell Titanal "something-or-other" - my "old-timers" is acting up & i can't remember the particular model). these poles are now broken & long since discarded. i also ran into this problem with one "joint" of my new REI CF poles.
i've found that, in all cases, this problem can be rectified. how?
1) disassemble the "joint" by loosening as much as possible and pulling the sections apart
2) tighten, or screw down the expander farther onto the threaded stud. this is the direction that i have needed to screw the expander in all cases. however, the number of times i've done this is not sufficient from which to draw any statistical conclusions. you might find that you may need to screw the expander in the other direction. i don't know for sure.
3) reassemble the sections
4) tighten the "joint" normally
5) if the joint doesn't tighten, repeat steps 1-4
i use my poles 4-6 times per week, every week. i've done this "repair" perhaps 8-10 times (a reasonably approx. number - i wasn't keeping score), over the first six months of last year. probably would have been more, but i finally decided to keep the poles extended. then in the summer one of the Komperdell Titanal poles broke. i replaced them with Leki Ti poles which never had this "tightening" problem. only once on the Komperdell poles did i have to repeat the procedure a second time immediately following my first attempt to correct the problem, i.e my first attempt that day failed to correct the problem & i had to repeat the procedure.
with the new CF poles, i had to perform this procedure only once on one of the four joints. i intend to keep these poles extended unless traveling by plane. of course, i still check them for tightness every time before use and periodically while on the trail. however, i haven't been using the REI CF poles as much as i anticipated because i still like my GossamerGear LightTrek poles better.