Binding brakes - Front caliper pots not going back in easily

[Bretty]

I rounded one of my master cylinder screws. Easily done when they are rusted in, brake fluid is incredibly corrosive.

I bought some reverse thread drill bits from b&q for a fiver and got it out pretty easy.

Can you get a service/seal kit for the master cylinder? That might be worth considering.

I would suggest changing the seals in the caliper but you say they are all moving freely.
Else it might just be worth bleeding especially If they have been binding and overheating.