In looking at all the white powder around the fracture point on the eccentric crank, it looks like there is considerable zinc corrosion. When zinc corrodes it expands. The sleeve around the outside of the eccentric crank is probably constraining the corroding zinc, which then clamping the crank insert. You may not want to try rocking the broken eccentric crank, as there is a risk that this will loosen the crank insert in the die cast wheel center. I am assuming that you were able to remove the screw completely and it is not broken off in the crank insert. If I was facing this problem I would probably try to cut the sleeve off the eccentric crank with a high speed Dremel abrasive cutting tool. Then grind, cut , file away at the eccentric crank shaft until you can get it off the crank pin insert. In my mind the challenge is to protect the crank pin insert as I would not want to get involved with trying to put a new crank pin insert in the original wheel center. I believe that both the eccentric crank and the sleeve were remade for the 1990 1-700E, and these parts are still available. Given the condition of the eccentric crank on this side, it might be prudent to also change this part on the other side.
To help minimize any additional corrosion, it would be best to keep your locomotive in a cool dry environment.
Best of luck to you and please let us know how it comes out.
