Gentle only, don't push thru any pain.
slow and easy is the best TOS way.
The tissues are restricted and stuck most likely, you can't just get crazy with stretches and see good results right away, it takes time.
You probably got TOS over time and so it takes time to change the body back to a more normal state.
I follow Sharon Butler's suggestion on any stretch or activity, only to a minute hint of a stretch sensation, nothing more.
In a short time you should notice that the sensation is not appearing as soon as it first did & that you are moving a bit futher each time.
Slow and steady is the best way.