The hole positioning on the main deck part 29 has been left deliberately under-sized to allow you to adjust its position front or back until the crane sits nicely upright, and its jib nose fits into the cradle on the front of the wheelhouse, so it is most important to check that this fits before you begin to paint the model. A couple of degrees difference between the model and the plan could result in needing to adjust the length of the jib, not an easy job once built