As I said, I could swivel the cover to service the filter. So this only works if you can get to the back side of the brass insert. What I did was take one of the free air box screws and put a nut on it. Then, i screwed it into the backside of the insert until it touched the stuck screw. I backed it out half a turn then tightened the nut against the insert. using two wrenches, one on each of the screw heads, I turned the stuck screw right out! used the wrenches to remove the back screw and jam-nut. I pu a little lube on the screws before I reinstalled them to prevent sticking in the future.
