Yeah, I was trying to get it out the big end
I was able to pry it out after considerable effort. It was really jammed up in there. I think I'll just be replacing that one. The out post on the same keg is in the same shape so I'll need to work on that one as well.
I haven't taken apart the other three kegs yet but I just went down and pulled off one of the posts from another one and it was fine. These kegs will definitely need some refurbishing before they can be used.
Which poppet valves should I buy for replacements? I've looked at a couple of sites and there seems to be some variety depending on the type of keg. Mine are pepsi ball-locks.