If the milk tube pops out of the splitter, this indicates that the connector and tube are too greasy. Clean the ends of the tube using washing-up liquid and dry thoroughly. You can do so by twisting the corner of a piece of kitchen towel around in the opening. Also degrease and dry the connectors on the splitter. The surfaces will now have more traction and the tubes will stay put.
NB: Breast milk is very fatty. The breast pump will only function properly if all parts are degreased. Silicone parts in particular can stick if they are still a little greasy.
Milk has entered the air tube. What can I do about this?
Flush out the air tube with water and leave to dry thoroughly. You can order new tubes from our webshop. The air and milk tubes are delivered together.