Part fell off Domino DF 500. What is it? Where does it go?

[zzzzdoc]

This fell off my Domino DF500 today.  For the life of me I can't figure out where it slides back on.  What is it, and where does it go?[attachimg=1][attachimg=2]

 

[ChuckS]

The first piece looks like to be this:

[attachimg=1]

Check your fence.

 

[zzzzdoc]

Both pictures are of the same piece. I’ll check it out in the morning. Thank you so much.