After a measurement is complete, the sample chamber must always be cleaned immediately. Should the yeast sample dry up in the chamber, the chamber may be permanently damaged.
This is a video on how to clean the sample chamber:
And here are more details:
In order to guarantee optimal analysis, the sample chamber must be cleaned and dried after each use. To do so, fill the included syringe with distilled water and then use it to rinse out the chamber.
Press the plunger down slowly! Otherwise the high pressure might damage the sample chamber, causing it to crack.
Lastly, the chamber should be dried using the included bellows. To do this, rest the bellows against one of the sample chamber’s openings and then press the bellows to blow air through the chamber.
To prevent water flowing back into the chamber, it may be helpful to insert tissue paper into the other opening of the sample chamber in order to soak up the expelled water.
Do not completely block the other opening with the tissue paper. Air must be allowed to escape, otherwise the high pressure might damage the sample chamber, causing it to crack.