I am trying to replace a carburetor on my Briggs and Stratton 12 1/2 HP ride on. I cannot get the carb mount studs loose. they are recessed. the deep sockets I have used are too thick to fit into the recessed area. I have tried to use a box wrench to grab the little bit of the bolt protruding but its not working and I dont want to strip the head. I tried a 5/16 nut driver with no success. I have seen videos that say use a 5/16 others an 8 mm in either case I'm stuck. Do they sell the correct wrench for this? Any suggestions on how to get these out?