This is mostly it. Plus you have to remember all the documentation lies in a 30 year old system. A new hire isn’t going to be easily able to piece together all

This is mostly it. Plus you have to remember all the documentation lies in a 30 year old system. A new hire isn’t going to be easily able to piece together all the details quickly. Then there is all the stuff that is documented or not in procedures manuals and standard practices that they won’t know. Add in actual missing documentation like order of operations and special considerations that have down steam effects and i guarantee you would still come out ahead even if you are paying retirees 2x as much. The parts are no doubt expensive and any single screw up would likely be at least worth of salary expenses.