stuck huh, (prayer and lots of PEN oil)
do it steering wheel style
put 3/8 socket that fits. there, say 14mm what ever fts
the a metal plate, drill 2 hole that span 2 , 6mm thread holes in the cog.
i use washer or what ever, to get the screw heads to hit the top of metal bar
then she comes off just like a steering wheel .