Wow...lots of mis-information in the previous post.
Some years ago Steamtown (ST) had a policy which required that only ST crews would operate the locomotives. That policy was rescinded a long time ago. When the 765 ran at ST, NKP 765 crews ran the locomotive under the guidance of a qualified ST pilot engineer, same as when we run on NS. As to the OP's original question about operational roadblocks at ST, there were none.
The failed flue did not "burst." One flue had a small circumferential crack in it at the front flue sheet about 2" long. The engine steamed fine even after the flue failure. The only clue that something was wrong occurred during shut-down when we noticed a little water running out of the smoke box.
The greased rails at the tunnel did cause us to stall. We had to back up and take another run at it to get through the grease. I know the details because I was running the 765 when it happened. It had nothing to do with the engine crew being "...used to shorter trains..." whatever that means. I've run 765 with much longer and heavier trains than we had at ST. The New River Trains we used to run filled out to 34 cars!
We did not cancel the Tunkhannock trips. Those were not even "our" trips. We were only supplying the locomotive and crew for this one, that's all. The Lackawanna historical organization was the sponsor of the trip and sold the tickets. The trip was not cancelled because of insurance. It was cancelled for a very simple reason...CP said, "No."
If you are going to post info here about 765 and other steam locomotives at ST, you might want to do a little research first and get your facts correct.