The solvent keeps flowing into the titration vessel after the addition, without the add key being pressed.
Set the solvent bottle up in such a way that the fluid level in the bottle is lower than in the titration vessel.

Solvent is added simultaneously during aspriation.
The drying tube in the titration vessel is blocked:

• Increase hole on the drying tube cover to at least 2 mm
• Refill the drying tube, do not pack to tightly, possibly removing some of the molecular sieve.

The pump conveys no fluid.
Press the addition / aspiration key more strongly.

• In most cases the bottle attachments are not screwed tightly enough to the reagent and waste bottles
• Check all connections for leak-tightness
• Check wether the 803 Ti Stand has been set up correctly