[Arran]

Murf;
  Try touching up the solder joint on the 6B7 grid cap as well, and don't overlook the grid lead or it's clip, those things break internally near the grid cap clip sometimes. The 6B7 is a bit of an oddball tube, it's a pentode-double diode, just like it's octal cousin the 6B8/6B8G, not many radios used them, though more used the 6B7 then the later 6B8. Most manufacturers used a 6Q7/#75 or a 6R7, or if they wanted to tube stuff the chassis between 1936-38 they would use a 6F5 and a 6H6, more tubes equaled a "better" radio to the sales and marketing department. 
Regards
Arran