How To Change This Part, Brake Indicator? Help Welcome

My stop brakes are difficult to light when I press on the pedal.
There is only on part making the electric contact, others are not connected.
This part is easy to see, well located but I am afraid to make action on it.
See picture 1

This is on contact with the brake fluid : if I succeed in moving it off, will I be able to replace it?
Will air come in the brake circuit with all the trouble we know?

I have a new part, which I hope is the good one. See picture 2.

I had started to make and fix an electric contact under the brake pedal, I press the pedal and light works.

But the idea of changing the good part stays in my mind.

Please give you ideas...

 

You can just unscrew the old one and screw the new one in it's place.
In theory you may be introducing some air into the system but I have changed several of these without the need to bleed the brake hydraulic system.

 

I too have changed these by just screwing in the new one. Expect to lose a little brake fluid. No problem.

 

Happy to read this... I'll first spray some oil wd40/similar to prepare easy unscrewing

 

Ok thanks my brake liquid container is quite full. And all this is in upper part so all is positive.
I am just afraid to break something when moving this part.

 

Use two wrenches opposed to each other. One to turn the sender, and one to hold the junction block.

 

Well, all is done correctly. Thanks to all! I was afraid to break something, parts are difficult to get here, and specialists too.
Maybe these are the seame parts as for the Willys, I don't know.
I unscewed quite easily, with calm, put some brake liquid inside the sensor, then my wife helped me to ress the brake pedal, I saw the liquid coming, so that was correct.
Then I screwed the new part, my wife made the test, there was a small leak so I screwed a little more and... perfect.
You can see that the old part was in fact quite broken at one of the contact screw.
The stop lights are now working perfectly, before it was not working for light pressure on the pedal.
Pictures : the broken part and the lights :