Hi friends!
I heard about this problem several times, and after replacing the pliers I encountered it myself: during operation, when trying to open the pliers, one handle folds up, but the pliers remain closed. Tightening the screw reduces the problem but makes it very difficult to open tools such as a knife blade.
After suffering for several days, I sat down and tried to solve this problem.
So:
We take something similar to a small hammer (photo 2), take a folded multitool in our hand, and very, no,
VERY gently hit the flat part of the handle, which is indicated in pink (photo 3).
It is necessary to act carefully, knocked once - checked (unfold and fold the multitool), if necessary - repeat.
It was enough for me to make 2-3 times. After that, by releasing the axial screw, the opening force of the tools can be adjusted.
Note: you perform all actions at your own peril and risk. If in doubt, please contact your dealer