[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.