After a time, the metal fatigues and isn't as 'springy'. If you bend the contacts back, they dont seem to stay put very long. If you're going to open it up, just replace the jack with a factory or NOS jack.
If it's a vintage guitar, make sure you use a screwdriver that properly fits the screw you're removing. (But you knew that!)
70's is vintage?
I'm getting old....