On flick locks, there should be a screw or dial that can adjust the tightness of the lock.
I have Fizan twist locks. They have a plastic plug on the inside. It can not be adjusted, but could be replaced if they are broken (would have to find a place to buy parts).
For either type of lock, the work by friction either on the inside or outside of the pole, depending on the style. Dirty poles could interfere with this, so giving the surfaces a good cleaning may also help.
I have Fizan twist locks. They have a plastic plug on the inside. It can not be adjusted, but could be replaced if they are broken (would have to find a place to buy parts).
For either type of lock, the work by friction either on the inside or outside of the pole, depending on the style. Dirty poles could interfere with this, so giving the surfaces a good cleaning may also help.