Does anyone know where I can get transistors for a 30 yr old Spectral amp DMA200?

Might try Electronic Goldmine.  I found a Capacitor there for my wife's old sewing machine. It was the only place that had one.

Chuck 

You or your friend might first investigate the possibilities offered here, and then come back if the parts cannot be found.  Someone like Nelson Pass or Bill Thalmann may also be able to advise about a modern part that is interchangeable with the needed part.  Such newer parts are often better than the originals.  What makes you or your friend think that the latter two transistors are "near failure"?  Anyway, you guys have to do the searching and asking.

I've had luck finding obsolete semis on eBay. Just do NOT buy from China as they are most likely fakes. 

@chungjh if you only replace the bad ones (VN), then do you need the PN ?
 

@holmz thanks. It looks like they have the VN but not PN

It sounds like VN are gone but PN are not gone yet. I guess the VN's could be replaced and pray that it will play. Larger heatsinks are being put in.