It would have been too good to be true if it had worked
I don't have a scope myself, but often the service manuals (Sams or otherwise) will have diagrams showing what the waveform should look like at various test points in the set.
If you don't have that, then perhaps someone more familiar with the waveforms that should be there can point you in the right direction for where to test and what it should look like.
If the v. controls do absolutely nothing, then I'd check those as well before going resistor-hunting... Sometimes dirty pots can cause weird problems.