Would it be a mistake in the long run to leave deadwood/ dieback ? Trunk looks to be affected vertically - growth of branches on one side look healthy though possibly deadwood other side . New soil repotting 1yr ago . Concern is if leaving it as& not cutting down further to the green wood - risk the possibility of side branches also dying ? Drawn shows direction of Apex of Trunks either side of newly putty top centre - at the moment with an element of some flow. I’m also factoring that it Will also be Watering to be the deciding factor !

Having to investigate die back on middle trunk , & now apex is dominated by right trunk as previous years the left received damage. Warded the aphids off quickly with detergent & Castile soap