[Arran]

Jayce;
  If you take a look at the parts list there is very little in the way of capacitors to replace, most of the set seems to use ceramic caps, of course that still leaves the electrolytics and carbon comp resistors to deal with. The selenium rectifier is probably tired, I would bet if you checked the B+ voltages with your volt meter you will find that it's probably down at least 20% or more, be careful if you do though, this is a true hot chassis set.
Regards
Arran