The side plates should be able to be driven off the pins, probably just rusted in place. They lock onto the taper of the pins pretty tight by design. Put a punch as close to the pin as possible and alternate hits between the front and back side. Once they break loose they come off pretty easy. Probably best to start with the spring end because once you get the spring released from the frame it is hard to hold things to get the impact of the hammer blow to do anything other than move the whoel spring and whatever it is attached to.
