Starship Trooper

I recently acquired a Dynaco Stereo 70 Series II with one of the cathode resistors blown to smithereens - haven't done any further testing yet. Questions for the Dynaco veterans - 1 - Where can I get the parts, schematic, etc. to perform the screen resistor modification - and replacement cathode resistors? 2 - Is it safe to assume that if the cathode resistor is blown, the finals also need to be replaced on that channel? 3 - Why in the hell did I ever sell those Dynaco A25 speakers I had in the 70's? Thanks in advance Starship Trooper