What do I do? Battery spring fell off

I am trying to inspect a Sony Walkman WM-FX30, with lots of corrosion and alkaline leakage in the battery compartment. When I was opening it up this fell off. I looked at a guide and saw that the original piece and I had an idea of where it might go. it looked something like this. Do I solder it again (after cleaning the residue) What do I do?