Hi! Dissembled a "SPDT switch" (right name?) but do not know how to fix it back, where should the small plate be placed?

 

hi Daniel,
Welcome to AAC.
That bit is the slider, it bridges across the two brass rails on the green base.
The Black bit fits on top of the slider and the metal bit on top of the black bit.
E

 

The dissasembling part is easy, it is the assembling part that causes the problems.

 

Wow! Thx for fast answer, switch is now in place and the train toy is working again - and hopefully also some happy children in the house Thx!