One will still run into aged parts like switches.
at that point, the person doing the rebuild must really put in the work. some say that if one just sprays deoxit (or other ’cleaners/lubes) into the switches they’ll be fine.
my experience says otherwise.
When I do a very serious rebuild, I de-solder the switches and remove them, and then take them apart and manually clean and re-lube the sliders and contacts, then reassemble the switches and re-install.
this is insanely time consuming and no one will pay for it.
Then the extra bit is not just upgraded and new capacitors but upgraded resistors as well. to pull them ALL and put in non magnetic high grade high end audio equivalents. Every single small value film capacitor changed out to polypropylene non magnetic equivalents, film and foil and so on. Eg that to buy that level of quality of parts (just at the parts quality level, not the same circuit, of course) in a outboard phono preamp (which is in the 3120) would cost a good thousand plus. as a used item. not new. At least double, new. And you’d really have to know your stuff to find out how it is built and see under the hood of the prospective item, to check on that.
This is again, insanely time consuming (buying the parts individually, getting the right ones, making what is essentially design choices, and so on) and no one does this and no one will pay for it.
So I just do it for myself.
Eg, I have an NAD 3120 here, that I did this way. It’s like a 1000 hp 1g corner handling ’beats a Bugatti Chiron’ kind of sleeper. Meaning it looks stock. but it is not. It is the orignal circuit, to a large extent, but everything else is different.
The transformer and chassis and circuit boards, the switches and the like are the same. but the rest is all premium parts grade, at the luscious premium high end..er... end of the pool. Then the added in tweaks, the tricks of the trade that each of us have to try and make things better.
the kind of item, where if one could not see the faceplate or ’know’ what it is, it could be displayed at a high end audio show, in one of the rooms and everyone could come in and listen and remark on this new amplifier and the amazing sounds it is producing.
But this sort of work tends to get little to no respect, in my experience. I guess the closest known modern equivalent would be the guys who are taking specific models of reel to reel decks, and upgrading them to insane levels and selling them for $10-15-20k each. I believe we’ve helped that crew out with some of the chassis damping and noise control, at one point? Point being, is I’ve put that into this lowly NAD 3120, as well. Every kitchen sink of secret lore I can add in, is in it. Just to make a world class sleeper in a run of the mill chassis and circuit. Just for the fun of it.
By your posts in this thread (OP and the rest)... I see that you’ve come to understand that gambling and the ’no free rides’ sticker are in an act of convergence for you.
Back to the point at and. You’ll have to find the person who can do what you want and you’ll have to find it at the level you want and that person will have to be paid. and you’ll have to gamble on their skill and knowledge set and in the end you’ll be left with the switches. the dang switches. they age and almost no one knows how to deal with those switches.
You are looking for a very particular audio shaman with a very particular set of audio shaman skills, where you’ll have to decode their capacity as best you can and then, still, in the end, take a chance. An educated chance, with variables controlled and predicted as best you can.. but a chance none the less.