McIntosh MAC 1900/PSB 5T burning smell

Over 40 years units can go bad any minute any time. So claiming refund from seller would not be legit.
Smoke also goes from transistors mainly driving transistors.
I usually ask $200 + high priced parts if overhaul is needed.
I void shipping turnarounds and so advice you do same.
If you’re 1...2 hours of driving from descent tech, you should take the ride and give your unit for repair.
Be ready to stretch to $150...200 ball park. Also some claim examiners are pretty smart so they will note the age of unit and deny your claim.

Are you building a antiques-only system?  If so, maybe get the old Mac receiver an expensive repair, which will not be cost-effective IMO, but then you'll have the sentimental glow of an Olde Audio Experience. Surely the eBay (basically flea market) purchase was understood as an As-IS thing?  Let's be reasonable about this.  No way you paid a lot for this Olde boat anchor, right?  Chalk it up to experience and the inevitable risk of buying old stuff sight unseen. Sometimes eBay luck turns bad.  If you want real warranty and real buyer protection, well that costs real money, as it should. 

Or maybe spend a few more bucks and get a way more satisfactory modern product that doesn't need to be re-capped and will sound better? Many options out there, and not all of them super-expensive.

Good luck!

@j_stereo This is very helpful. I'll buy a multimeter tonight and do that. What range of output would be acceptable?

Eli - anything greater than Millivolts is too much, but you shouldn't even have to go that far because if there is any smell of heat or burning there is something wrong with the receiver. When these receivers are in proper working order they don't generate any substantial heat even when driven hard, and they definitely should not be generating any smell. I am guessing there is something wrong with the receiver to make these components get hot, and it probably should not be used until the problem is resolved or it may damage your speakers.

@j_stereo Thank you again for the help. I was trying to work around bringing it in because I was excited to get it and use it..but I think I need to bite the bullet..Especially with the potential for a house fire.