Some of the Lemon new 2-piece hihats give an issue after some time that the top-cymbal is not responding correctly anymore.
This is due to an interal loop-through cable where in some cases has encountered a production issue. To check if this is the issue you are encountering, connect the top-cymbal directly to your module instead of the internal loop-through connector. If the issue is resolved, it is the internal cable that needs to be replaced.
Replacing the internal cable is fairly easy. Follow the steps in the video below: