The stuff we had was too small and would clump if you didn't sprinkle it on one shovel at a time. Otherwise it worked pretty well, at times too well and the pop would go off even with the injector on. You had to work to make it smoke a lot. Passengers in the open car on the way north appreciated that.
The fire needed to be cleaned out thoroughly after a run. If you didn't the next run would be frustrating, as the ash in the bottom kept the fresh coal from burning the way it should. Dumping more coal on didn't do much at that point and the gauge would sink slowly as we worked north up to Alna.
Every time we get a new load of coal it's a new routine. Keeps it interesting, that's for sure.