Old SS amps

@emergingsoul 

Manufacturers of electrolytics usually say shelf life is 2 years but it depends on storage conditions, mainly temperature. It's generally accepted that the rate of electrolyte degradation doubles every 10 C increase. In addition, high humidity causes lead corrosion. Climate-controlled storage is pretty critical.

Personally, I would restart anything that hasn't been turned on in a year on a variac.

A variac is absolutely the way to go if not sure about caps, you can reform then through a process of starting off with low voltage and increasing in steps. Also, I'd open up and visually check every cap, look for leakage, swelling.

@devinplombier 

Fascinating your knowledge on this.

So basically the older wine bottles I opened a few months ago, all bad and disturbing, are foreshadowing problems I may have connecting some pieces of equipment I haven't used for years. 

I’ve just finished restoring/tuning a Yamaha Pc5002m, better than spec and 8.5 looking. I’ve two driving the music section and a Pc4002m on the movie section. Certainly I’ve head room, no strain for anyone. The 5002m’s are truly audiophile be it in PA clothing, a marketing decision a.k.a. 101m reface. All three have had very time consuming and detailed refurbishing. Not a lot of technicians can or are willing to work on these, the detail justifies their spec sheet. Old to some, boat anchors to others, missing the bells and whistles of modern…time spent (hobby) irrelevant, its  about the sound quality. The make doesn’t matter if it’s liked and breaks ya fix it new or old. 
 

Cheers 

Often manufacturers would glue caps to the PCB. Although you'd like to think they did this for the sake of microphonics, the glue was there to hold the components in place while they were being soldered.

Sometimes with age and heat that glue kind of decomposes and spreads out over the PCB from under the cap. For all the world it looks like the cap is leaking, but it's not, it's just glue. 

Not that glue is necessarily benign: in rare cases it becomes conductive and causes short-circuits.