Chuck you have shown yourself to be a tinkerer, Google Micro-tig welding, I believe you could learn that pretty easily. I've never performed low pressure or vacuum micro-spray welding. The safety and weld environment aspects are tough, so if someone has a shop doing it, let them.
Reading about them and doing them are two different things of course. Takes about 5 years of practice to get any good at any of them. Anyone doing either technique every day is worth their pay. Combining that with knowing why the joint is loose, is worth even more.
These are low deformation, low heat techniques that protect the base material. Perfect for old gun parts, old door hinges, classic cars, motorcycles, etc. Surface pitting can be filled too, but time is money. How far do you want to go?
Like any tool, correct choice of application is called "skill".
With so much internet chatter about looseness, I'm surprised more people don't study surface restoration more thoroughly. I'm beginning to theorize that much looseness is in the original design, and we miss-apply our vetting rules.
Welding under a loop is done before you have a morning coffee.
