If you have replacement screws ( and you should if you are rounding out the socket also) just drill out the head of the screw. Use a drill a bit larger than the shank of the screw. Drill in until the bit gets to the point where the shank of the screw meets the head of the screw, then the head will pop off. Repeat on the other screw, then remove the head. There will be enough of the shank left above the cylinder to grab with small pliers and finish backing them out. You just need to sure you are using a good quality drill bit, as the socket heads can sometimes be fairly hard.
Type at you later,
Dan McEntee