Repainting the stove

The stove and its flue have been looking decidedly off colour lately - where the colour in question is black. There's been a fair amount of rust appearing.

This is where the flue joins the stove - after I wirebrushed it.

Should I refill the joints? And what with?

Just before leaving the boat last week I painted it with Calfire Stovebright high temperature paint...

... which makes it look better, but I think I should probably do something about the joints before using it next.