Pristine Mac 50+ year old C22 preamp bought used in 2000 off somebody, via eBay in CA..
Checked it out on my bench before placing in use.
1 festoon bulb bad, replaced both after Mac sent me 4.
Probably sprayed all controls and switches, whether they needed or not.
Even had all the original Tele tubes installed, and they still spec`d out !!
All electrolytic PS capacitors were, and still are in good shape, surprisingly !
I run it driving my "non used anymore for fires, fireplace" placed rotational tube amps(MC 30`s, MC 225, ARC D76A, 2 pairs of Dynaco Mk. III`s, all amps reworked) at least once a month for around 16 hours or more, in fact it`s running right now sending sweet WAV. sounds to my DQ-10`s in my Sunroom.
Mac 50+ year old MR 67 tuner, bought from AC, via Frank Gow (RIP) in 2000, and it didn`t appear to have had anything done to it, with the PS caps still original, as well.
The last time I checked it out on the bench it still was in spec, though I quit listening to FM back in 2010 when I had my attached car garage`s Sony receiver(also has run 27/7 since install in 2000
) hard wired fed for L/R distributed signal feed from my living room`s main A/V rack.
Before that I had built a Ramsey kit TOTL FM transmitter for feeding my living room`s rack`s audio to the garage(93.3 Mhz. "WBIL", as my friends called my 100 milliwatt output station, and I would monitor my FM signal`s quality with the MR 67, as I thought my music programing was better than my local commercial FM station`s offering`s..
One of the several reasons I like, own , and use Mac gear a lot.
Now my purchased, used in 1986, MC 2205 needed it`s main caps replaced as they started dripping electrolyte, 2 years ago, and the front panel bulbs + the AC inrush Thermistor, but it runs 24/7 too, being driven by a circa, early to mid seventies, also 24/7 running, C27 preamp, in which nothing has been done to it at all, outside spraying controls/switches before placing in use, after full bench check out.
I love to own and use used electronic gear that I don`t have to usually work on, probably why I test the crap out of it before placing it in service.
Enjoy the music, as you see fit folks.
Kind regards, OKB
EDIT : I forgot my about my purchased brand new in 1986~87 Mac MCD 7007 CD player, with nothing done to it but a voluntary LED front panel upgrade 3 years back.
Ran it today for about 4 hours S/PDIF connected to my DAC, and it`s analog output to my C 37 in the same rack to check 4 Gino Vannelli CD`s before ripping them to my WAV. music files.
I usually use my OPPO UDP-203 for CD playback testing prior to ripping, but thought to check it out, and it still performs properly and sounds very good.