Restoring the original DualShock for my restored PlayStation 1 --- AF invention

I needed a DualShock controller for my restored PlayStation 1 so I wanted to do a restoration and repair for one. I got my hands on this abandoned DualShock controller for the PS1. It was sold to me as working but, as usual it was broken… The shell is also quite badly yellowed and dirty. Couple of the screws on it were rusted.