[Arran]

 I think I have an S-38A, or a B, I also have an S-38. The S-38 has six tubes, the sixth one for the BFO, and it has an extra knob for a BFO adjustment, the A and B are similar to each other with more minor revisions. That blown resistor, was it under the 35Z5 tube? If it was then it was used as a sort of surge protector between the power line and the plate of the 35Z5. In any event there is tons of service info online for the S-38 series, at least up to the C or D model, even now they are popular sets to restore.
Regards
Arran