Hi Bill

Are you talking about the white bone bits (saddles) or the flat strips underneath them?

There will be one white bit with a rounded end that is lower than the others. That should fit the treble side of the saddle slot.

The other two bits will go in the longer slot, the rounded ends at the end, and the lower one in the middle and the tallest one on the bass side.

If they fell out they are too loose. Shimming them to fit just right is a specialist job. Luthier. I recommend Brian Rodgers in Walderslade, Kent.