At the base of each section, there is a band of tape which prohibits the user from overextending the sections. Over time, this tape starts to loosen and bind up inside the pole. You’ll need to pull the pole sections all the way apart and remove the tape. What I do with mine is remove the tape, then mark a band near where the tape was with a sharpie. That way I can see when I’ve extended the pole as far as it should go.
Same thing happened on my SL-X. Twisting clockwise loosened one section up. The other section I had my brother help me twist it (him on one end, me on the other) as it was REALLY locked up. We wore WR gloves that I had for grip.
I think proper maintenance is really important though… part of the reason it gets stuck is sand/grit getting into it, whether from the hose being internal (I always keep mine external) or from being in a dirty truck/van, getting crap in the base and it working its way up, etc.
If you don’t maintain expensive items, they often don’t perform at high levels. That isn’t necessarily bad design.