Great gesture for your bro, NJ. How hard was it to restore? Were the boards easy enough to get access to and reach the backside without major de-soldering? I have one too and someday I may get around to restoring it.
Seems to me that the 1900 isn't as highly regarded or highly priced as some of the other Mac receivers (1700, 4100). Unrestored, they seem to go for $500-600, and restored by someone trusted, maybe $700-800. Wood case might up that a bit, but $1000 seems like a stretch.
I recently heard a fully restored MAC1900 for the first time and IMO, it's as worthy a McIntosh product as any.
Product aesthetics tend to influence marketplace desirability/value and the MAC1900's oh-so-'70s slider tone controls definitely have more detractors than fans which are usually associated with more downmarket audio products of the era. Same for the rows of black plastic pushbutton controls.
The MAC1900 is a superbly engineered receiver otherwise with an excellent tuner section which shares technology with the revered MR74.
After hearing one, I would take an MAC1900 any day.
Honestly,
The 4 boards on top pull out. 3 vertical ones,
2 are held in by 2 screws, one by one. One held by one. Tuner board on stand offs. You need to squeeze barbs to release. Stand offs are brittle ( probably more so now 30 years later). If one breaks don't freak. Mac has them for a buck a piece and mouser has them for a dime a piece. One board on bottom you have to cut a few tywraps and unsolder (3? Maybe 4?) Wires.
Really easy to work on.
Cohibajoe had a good thread I aped
I had one too.
Feel free to reach out before you dig in and order parts maybe I can spare you some effort.
Sorry for the sidetrack OP
Still have the 1900...I sold the 4100...For me the 1900 is that Perfect Mid-Town Manhattan 1 Bedroom receiver.I had a 1700 several years ago. I just restored a 1900 (i bought for my brother for retirement) Its still sitting here. Personally i like the 1900 better than the 1700 (though the 1700 wasn't restored so perhaps an unfair comparison). The little research i did seemed to put a clean 1900 somewhere in the 7-9 hundred range. I never heard a 4100 but based on reports its the sweet spot for mac receiverdom. (At least in the vintage market). I know Frank Mcintosh never wanted to put the Mcintosh name on the receivers (hence the Mac model #s) They're pretty nice! As with anything else , you're likely to get differing opinions.

Marantz 2275 has plug in boards you might suggest that if he wants Marantz its kind of 50 50 between that and the 2270 from what i see people saying they like better. they are both awesome receivers.I'd much rather work on the Mac's plug-in boards.