More work...
I plated over the FM exhaust port. That's probably what they would have done, since it would have been the cheapest and easiest.
Also used a hole punch to cut 1/4" discs from styrene. Then reamed out the hole from the cut off steam generator exhaust with a 1/4" bit, and forced them in place and glued and stacked and glued.
It should sand down nicely.