The refill plug should be open, so the electrolyte inside can flow through the diaphragm into the solution.

Dear Soumita Deb, In general, please make sure that the filling port of the electrode is closed during its storage to avoid loss of the electrolyte solution through evaporation, which can cause the formation of crystals within the electrode and junction. If precipitates are present, replace the electrolyte according to the video. If electrolyte crystals are still present inside the sensor, these can be removed injecting with a pipette distilled water into the emptied sensor (through the filling aperture), shaking the electrode, emptying it from the water and refilling it with the specific electrolyte. For long term storage, keep the electrode wetting cap or tube (electrode holder) filled with the inner electrolyte solution, pH buffer 4 or 0.1 mol/L HCl.

@@METTLERTOLEDOLaboratory what should i do if there is crystallization already? How do I clean it up?

Hi, All of our sensors have the correct electrolyte printed on the sensor head. In this case, it is 3M KCl, AgCL Salt, as seen at: kzfaq.info/get/bejne/ibGSdKh6mMnNmXU.html