Heeeeelp! This piece is loose and I can’t make it stay put.

Thanks for the question.

The bobbin bracket has come out of it’s holder. This happened when you were probably  removing the bobbin case to clear thread from under it.

You have a Singer Touch and Sew machine manufactured after 1964. The Touch and Sew was the first machine that had a built-in bobbin winder. Many love the ease if threading the machine once and being able to wind the bobbin.

The bracket in question is held down by a spring inside the machine.

The bobbin case bracket needs removing.

To reinsert it,  slide the bracket flat under the machine until it snaps around the adjustment screw.

When you wish to remove the bobbin case again – lift the bobbin case bracket and slide it into the machine, resting it elevated on the adjustment screw.

You can then slide the bracket back into place (having it drop over the adjustment screw).