Screw removal on center brick of Quad Santa Fe

Hi, giving my stove the yearly thorough cleaning, and the allen screw that holds the center brick in place seems to be frozen. First, is removal recommended, and if so any ideas on how to loosen it without stripping the head? Thanks, it's early, but gearing up.

Daksy, thanks it worked, all i had was wd40, but it did the trick. Thanks guys, what there is behind there is a small space with some screws which i guess secure the hopper, not sure. There was a small amount of ash in there. All set for the season! Heads up, there seems to be an increase in the price of pellets this year. I'm not going to repeat last year, in Sept there will be three tons delivered which will hold me.