Broken front derailleur 7400 Dura Ace The chain came off a couple of times while I was riding yesterday and when I tried to put the chain back, the small screw came off from front derailleur.

I think maybe that’s a thing to attach the plate and where it moves. 

Is there any way to fix this problem?
You should connect the holes visible in fig. 2 using the screw in fig. 1. It is not very well visible, but the small piece should accept an Allen key and it is screwed from the rear side (see first picture below). It should ultimately be screwed into the bigger piece marked in the other picture below.



I marked the relevant place on a photograph from pedalpedlar.co.uk. I hope this counts as fair use.