The thickness of 2 mm is important, as otherwise the contact gap in the gearbox is not exactly right and the switch will not work reliably.

Comparison number switch 61 31 1 243 097
Comparison number sealing ring 61311355262

A little tip:
If you are not sure which switch is installed:
Press in the ball head. If the switch has continuity, it is the old version, if the switch has no continuity, it is the new version from 9/75 onwards

Information on product safety