Hi Chris,
Don't loose heart!! Changing all the capacitors is really only the starting point for a restoration
Only once all the caps likely to cause problems have been done can fault finding & repair actually start!! I don't even apply power until I've tested/ replaced likely caps, done cold checks on resistors and potentiometers, reformed/ replaced the main electrolytics and heated up the line o/p transformer. By this point there is a fair chance that nothing nasty will happen when power is applied and that the LOPT might survive! There will still be a whole bunch of faults to sort out until good pictures and sound are achieved
You have done well to get to this point, but now you need to apply some more methodical fault finding. Study the circuit diagram. Measure the valve voltages: are they roughly what would be expected on each IF stage and also on the video amplifier?
You may have one or more faulty valves which will add to the confusion!! Measure the windings of each IF transformer for continuity (with close reference to the circuit diagram) These can sometimes go open circuit as the wire is very fine.
It's well worth studying exactly how the signal side of a TV works and how the sound, sync pulses and video information is extracted from the original RF signal at the aerial input. This makes fault finding much more meaningful and rewarding.
Good luck
All the best
Nick