[Arran]

That is one style of capacitor that I have not figured out how to restuff, a Solar "Sealtite" cap. I always figured that the Solar "Sealtites" were kind of like a carbon resistor, that they were molded and there wasn't really a way to get them apart. One strange feature about the Sealtites is that they are one of the few vintage capacitors that I have encountered where many are still functional, which is interesting since Solar was apparently a cheap brand back in the day. 
  Speaking of difficult to restuff, there is a guy on You Tube that demonstrates how to restuff those older plastic molded capacitors, such as the Sangamo "Little Chiefs", and the black bumble bee caps (Sprague?). I don't know how practical this is but it clearly works, he cuts one end off, and then drills out the innards with a drill bit of the appropriate size.
  The restuffing I do isn't exactly museum grade, but I hate the look of yellow caps or brown/orange drops under an old radio chassis, especially if it's a pre war set, post war I care less about.
However in the case of a Canadian RCA-Victor A-30 I am working on  I don't care since I'm not planning to keep the thing, and someone already had a go at recapping it in the early 60s so most of the originals are gone. It's a six tube console from 1940-41 and is not rare, nor valuable, but I'm doing a quick and dirty job on it like some of the Fleabay and Radio Attic sellers do and have it come back to bite me.
Regards
Arran