I've done the next stage of testing.
I have left the LED in the circuit to make sure the add on oscillator keeps oscillating when hooked to pin 8 of the second stage of the tube (valve).
So with the add on board hooked up to pin 8 the board keeps oscillating LED keep flashing, but there is no effect.
The amp has the same sound with and with out the oscillating circuit connected.
Turning the depth pot does not cause the effect to work just makes the volume change slightly at the two extreams of the pot it is the loudest if the pot is set anywere else the volume is reduce slightly. I also tested it with the LED removed and the collector reconected to the circuit directly.
Rick what does the last section of the circuit do in relation to the second stage Cathode? The section I have circled in the diagram, the voltage divider.
Does it create a modulation ( vary the resistace to ground from the Cathode), which would causes the gain to increase, decrease, increase, decrease........
Or does it connect, disconnect, connect, disconnect....... the Cathode to ground?
Keep in mind my ValveCaste ris using 157 volts to the anode plate so the current though the tube would probably be higher, I'm thinking I may need to ajust the resistor values in that last section to make it work.

Thanks
Glen