It's boring, but there are hundreds and hundreds of different, very small spare parts for which the Ukrainians don't have the intellectual property rights and therefore the CAD drawings to be able to produce them. They don't know the heat treatment or the tolerances of a lot of their Soviet legacy equipment that is breaking down. Equipment that's being provided by the international community is also breaking down.
At the moment, Ukrainian commanders are having to decide between sending a howitzer back to Poland and not knowing when it's going to come back to them, and therefore losing the capability completely, or continuing to operate it even though part of it is damaged, which then leads to the system becoming broken in a much more serious way.
Working through that complex maintenance and support process for the equipment we have already provided, as well as ammunition and barrels, is the very kind of underappreciated aspect that we are struggling to follow through on.