Need Marantz Tech

I am posting this for a friend of mine thats up there in years now and is not on the internet. He has a Marantz 19 Receiver he has had since new. Finally it is beginning to glitch at times. Such as a channel dropping out, then coming back on and a few other niggling things. Is there anyone out there that has the skill and the knowledge to service this great classic from Marantz. I would hate to see a hack job done on this. The unit is absolutely pristine. The scope still works, but a wee bit dim now.

I have checked this out for loose or corroded connections and that is not an issue