After a couple of weeks off this ordering bits and recovering from flu, I've managed to spend a couple of hours with the amp again. With the aim of looking into the issue of the reverb. I did change one of the tremolo caps for a 0.033uF, which made no appreciable difference. I'll swap the other two next time.
As for the reverb I've checked the tanks transformers and they seem fine. I had managed to solder a signal wire to the ground . I thought that may have sorted it but no. But I am getting the crashing noise, if I tap the tank, now. So the return part seems to be working.
Next week I should receive a new pair of output valves, some caps for the tone controls and a couple of other caps.