WOULD IT BE DUMB TO BUY A MARK LEVINSON NO 23.5

@testpilot
Yes, taking anything apart can be a pain. Try real consumer gear, made to NOT be fixable....
But I would not have expected them to obscure parts values, unless its a very unusual, secret way of using a part. But cap voltages? really? That also means they are buying custom runs - which simply drives up cost on parts that one ought to be able to get from distributor stock.

I had a JC-1 and some later stuff that was clear as day. But that, admittedly, is ancient history.
Anyway, if they are, its a good point.
I'd just measure the DC values and work backwards though.  they can't obscure those!

I did it. I bought it for 2 grand. Its playing now over the the Martin Logans. Thought it would be harsh with the Logans. It's not. Its lush. I knew my Logans where an open speaker but now its wall to wall soundstage. The delicacy and detail of instruments. The air. Oh, and in all the excitement I forgot to hook up the REL SUBWOOFERS. Thought they were playing the bass is out of this world. 30 year old amp? Bring over anything to try beat this!!! Oh and MEYER AV in Los angeles is one of the few authorized service centers for Levinson will do a rebuild for 2 grand. Its going there this month. I will be in it 4 grand. Doubt anything can touch it. LEVINSON IS THAT GOOD!!!

Check the capacitors for leaks, bulging, etc. If you don’t see any problems, you should be good. It is one of the better amps around and can drive pretty much any speaker. And it has a beautiful midrange. This amp bring the best out of voices with tightly focused image and clearly defined boundaries.

It has plenty of slam. Don’t worry about some of the issues mentioned above. If it ain’t broken, don’t try to fix it. When the time comes, it will let you know if things needs to be changed/upgraded.

Considering the age of the amp, my suggestion is turn this off when not listening and turn on about 30 mins before a session. There are reasons to leave solid-state amps on all time. But not this one. Heat from the unit can do more harm to the older electronics.

We listened to ML amps when we built some of the stands for his HQD system in the 1970's:

https://www.google.com/search?q=hqd+system&tbm=isch&source=iu&ictx=1&fir=oDvvwsSTPRC3eM%253A%252CYNcqBNbhtX4oTM%252C_&vet=1&usg=AI4_-kTvSmSyU72Kn9fIJDtJx6fVRY3-Vw&sa=X&ved=2ahUKEwiahMql9KjnAhUUa80KHWkjBqAQ9QEwC3oECAoQGg#imgrc=oDvvwsSTPRC3eM:

Compared to Audio Research (tube, of course) and Bryston, as well as Crown, SAE, and other solid state amps of the day, it was OK.  The Bryson's sounded better to us, but you have to judge.  I was very unimpressed with them on Maggies for all the areas you look for.  They were a bit shrill, slow, and sounded hollow to me.  Reminded me of the difference between a Nakamichi 1000 and the vinyl (no digital in those days).  The Nak was perfect in reproducing what was recorded, but had a "hollow" backsound to it.  ML amps did the same for us, but you decide.

As others have posted, it is a very expensive part to service regardless of the downstroke (initial price).  I think for 2500 you could get a better product, but you have to decide.  

Have you heard one on your system IN YOUR ROOM?  Makes all the difference, of course.  Be bad if you got it and it did not meet your needs or expectations.

Finally, why so inexpensive?  Buyer beware!

Cheers!

At 30 years old, I would look elsewhere.