From FAQ on Leki Site:

“ My Expander Poles Won't Lock"
[this is a statement, not a question]

› Pull the pole sections apart.
› Locate the expander and hold with thumb and forefinger.
› For SLS poles, turn the pole section while holding
the expander, and check to make sure there is
movement of the internal piece on the screw.
>If you see no movement, or the expander appears
to be jammed, call our Customer Service
Department at 800-255-9982 x10.
› For standard expanders that come off, check to
make sure the screw threads are free of debris,
and re-thread the expander.
› Put the pole sections together, and continue to
tighten the desired adjustment until resistance is met.

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To this I'd add:
>It's good to memorize these instructions, if you understand them.
>Good luck with de-icing.
>Black Diamond pole design is totally different, relatively trouble free & idiot-proof.