Replying to Fks heel arm disassembly

Hey guys. So I've got a pair of fks, and one of the arms that connects the dildo to the turntable assembly has a stripped thread housing on one of my heel pieces. I've unscrewed it all the way on both sides until the dildo came off, but I can't seem to figure out how to get the thread housing part of the arm off of the heel. I have a replacement one right here, I just don't know how to swap it out and apparently neither does google. Can anyone help me out?