[Tucker]

I have a 40-180 console that was restored in the mid 80’s by someone else. I bought it from the person who had it restored back then so I know how long ago it was done. I looked under the chassis when I got the radio a few years or so back and somebody did a nice job on the recap with all wax paper and filter caps replaced. 
Just recently the radio started to play fine for 20 - 30 minutes then the station fades to nothing. 
Today I pulled the chassis and tested the tubes but all are still good. I’ll check the resistors next but I noticed that the wax paper caps were replaced with Mallory “Plascap” and Sprague black beauty caps. 
Are these plastic caps know for going bad or leaking?  I’m thinking of just replacing them with modern yellow caps since the plascaps are large enough that I wonder if they’re wax paper unde a plastic shell.

[Tucker]

I cut one of the Mallory Plascap’s out of the radio and opened it up and found out it’s just a paper / foil capacitor with a plastic shell.

[Paul Philco322]

So are you going to do the rest? If you do you will be good for a loonngg time....................

For prolonged use even the newer caps may need to be replaced, they were probably NOS when the guy did them in the 80's.

Good luck. 

Paul

[Tucker]

I’m replacing all the paper foil caps with new. I also found out the Bakelite block still had the original caps so they’ll get replaced as well. Then I’ll add a fuse and new cord to finish up.

[Ron Ramirez]

As Alan Douglas once said about selenium rectifiers...

How can you tell if a Black Beauty cap is bad?

If you remove it and toss it into the trash can, and it makes a noise as it hits the bottom of the can...it's bad.

In other words, all Black Beauty caps are garbage. Replace them.

The same advice goes for any other plastic cased capacitor from the 1950s-1960s. Just replace them.

As for the AC line Bakelite block, you should use X1-Y2 safety caps such as these from Mouser Electronics:
https://www.mouser.com/ProductDetail/Vis...XR8Q%3D%3D