I had that same problem. I drilled out the screws but the center v-support metal inside was rusted solid to the frame. I took a skinny cutoff wheel in a dremel (I think they are 1" in diameter and about a 1/16" thick) and cut a slit across the holes to the edge of the opening in the middle of the frame. That enabled me to pry it open just a enough to get that center v-support metal out. I then had a welder tig weld the slit. Then I blended the weld with a file and redrilled the holes and bought new center v-support metals. Sounds kinda laber intensive but those frames are expensive......like around 300 dollars.