There are three pieces that make up the center floating axle end play adjuster, the two side peices and soft center piece that needs to be flattened or centered punch, swollen into place after the other two pieces are in the hole where they go Dr Diff on here sells that assembly new I use to use thick axle grease, wheel bearing grease, to hold the two center peices in before I knew where to get the soft center retaining piece The only bad thing about using the grease is the two center peices can stick to the axle ends when you pull the axles out the next time BTW, I use a long, powerful stick magnet now to remove those center pieces to avoid dropping them into the axle housing, like you had happened IHTHs My message is your not the first person to have them DANG center shoulder ends fall into the center section IHTHs