If the device hangs upright on the wall, you can remove the transportation lock in the reagent cartridge receptacle.

The transport lock in the reagent cartridge receptacle should prevent you from losing the magnetic stirrer inside the device.

Please remove the transport lock not before the device hangs upright on the wall.

The magnetic stirrer must be positioned on bottom of the cylindric part of the reagent cartridge receptacle.
If the Colormetry is operated without the magnetic stirrer, monitoring cannot be performed properly and an error message
"F281: incomplete reagent injection" will be displayed. 
In case of lost, a replacement stirrer is provided on the backside of the unit`s cover plate.