1. I would start with wire brushing any crud off the ball if there is any.
2.Then apply a small drop of oil to the ball.
3. Clamp the drive square in a vise as someone above said.
4. Keep repeating oil and clamping until you can press the ball with your finger or get a socket on it. (Be sure to keep dirt out while doing so).
There should be no reason to pre- soak the ratchet unless it's super rusted up.
If the ball stays collapsed inside the drive square then you know the spring was shot to begin with.
I don't know that your ratchet is rusted but from experience smaller tools are harder to revive if they are in bad shape.
I'm just gonna guess you've never done the ATF soak?
For ball detents, moisture gets into and behind the detent and seizes it, teh ATF , with it's low viscosity as well as detergents can get into the back side of the ball the same way the moisture did. Soak also means lack of oxygen and 360 degree permeation. Thus why so simple yet affective.
I just did a Husky USA 1/4" ratchet I borught back to life with the ATF soak. Worked great but took time and patience.
It's not so much mega-rust, but that the oxidation takes place on vital componenets within the ratchet that render it unuseable or useable in only one direction.
If any bits are hanging up, I do the ATF soak and get things working, then tear the ratchet down and clean, asess and lube and reassemble.
For ball detents heat via a propane torch can also help before trying to push in once teh traditional penetrant method is tried. The heat can often break the metal oxidation bond, just like with fasteners.
Use what ya want. Try what ya want.
I just know what works for me.
And really--that all that matters--to me. LOLZ.