Aged components / service!?

I buy mostly used gear downstream of my source components. If you are technically inclined, its not a big deal. If you are the type to wig out when a unit isnt perfect, keep it to1-5 years old. 
For mid-fi to high end, almost all equipment using standard electrolytic caps from 1990’s onwards are good to go. Just do a function test. Recaps from this period is seldom necessary as the quality of components dont fail like 80’s and earlier. 

For units using paper and oil caps, I’d factor in that these may fail 10 years onwards. The neon green Jensen caps are really bad at this. I’d still buy it if I had a technician I can rely on handy. The caps cost any where from 25-75 bucks a pop, give or take. I’d still buy an old Audio Note amp if a good deal came my way.

I would not hesitate to buy an old turntable using the same rules. 

My one exception is that I would avoid 90’s Audio Research tube power amps like the plague. Some of these fail over and over.

For digital, Im always looking at new or a couple
of years old. I havent shopped for a disc transport.

I selectively bought some of Yamaha’s best equipment 
made. Serviced cleaned if needed and all in service without failure for 10+ years. I’ve two rooms using some duplicate equipment. If it’s reputable solid and top-of-the-line it will work better than most out there today. Top performing for a fraction of the price works for me !

Cheers 

In a backup system, I’m using a concept 4.5D receiver as a pre-amp. It was manufactured new, if memory serves, during the Carter administration. The unit works just dandy, as a preamp. The amplifier section takes a while to “warm up.” All original everything. Everyone’s different, but 10-15 years doesn’t scare this fella in the least. 

Add it all up, certainly best to buy brand new with warranty and live with it forever.
If your going to spend  it money on used anything then have it serviced well that could add up to a brand new piece 😏 I guess add it up whatever your willing to spend..