I posted another comment with the same basic content -
Reopen the A-10 production line. But, don't just start producing the exact same aircraft. Electronics have advanced astronomically since the last A-10 was built. So, we improve the electronics. Maybe we can improve the air frame a little - so build in the improvements. We might be able to grow the fuel system a little, addressing the complaint of limited range. The wings are probably already strong enough, we could probably add external fuel pods to get more range. Hell, we might be able to improve the pilot's view a little. Can we give the cannon magazine any more capacity? Might we add any thrust to the engines?
With the new aircraft, and new parts, and new logistics lines, we will have addressed your father's complaints of old, worn out, damaged, stressed components.
But, the basic engineering is solid. Start production of the newer, improved A-10's. Roll out a thousand or more, and get them out to the fleet, and the troops.
If the Air Force doesn't want A-10's, the rest of us don't give a flying fuck about the Air Force. Everyone outside of the Air Force upper echelons loves these craft.
Even with the cost of retooling and reopening the A-10's production line, we could probably build five of these for the cost of a single F-35. Ignoring the cost of tooling and opening the production line, we can build ten or eleven A-10's for the cost of an F-35.
And, no matter the level of technology, often times, numbers count. Five A-10's can most certainly fly more missions than that one F-35, even if everything else was equal. Of course, everything else is not equal. The A-10 is a superior weapon platform for ground support, hands down.