Remington 11-87 Action Spring removal problem

I have an Remington 11-87 that I wanted to replace the action spring. It is a 20 year old duck gun. I removed the butt bolt and the butt stock. I removed the action spring plug pin, but when I tried to remove the action spring and action spring plug the plug was stuck. Even with the pin removed the plug will not come out. It is the old style with the slot in it. I put a flathead screwdriver in it and I cant get it to turn. I put the buttstock back on and left the pin out. I slammed the butt down on the ground with the action open so that all the force would be against the plug, but nothing happened. I think there is rust between the action tube and the plug and that is causting it to stick.

I reassembled it and soaked it down with WD-40.

What ideas do you have to try to get the plug out? I thought about soaking the tube in some sort of fluid, but I don't know what. I thought about trying to push it out from the other end, but there is no straight shot through the receiver.

I had the same exact problem. I took a long skinny screw driver and pushed the plug down, then took a round file and lightly filed the spot I thought it was hanging on. I pushed the plug all the way down and just pulled the screwdriver out and the spring popped out.