Siemens SIRIUS 3RT Manual page 208

Mounting
7.4 Contact piece replacement (sizes S2 to S12)
⑪
⑫ ⑬
/
208
Slide the new movable contact into the contact piece support.
⑭
/ Slide the front part of the contactor back onto the rear half until the retaining clips
engage.
SIRIUS - SIRIUS 3RT Contactors/Contactor assemblies
Manual, 09/2017, A5E03656507120A/RS-AE/006