Have you tried to get a signal out of efx send into another Amplifier?
This is a rather complex setup and for those starting out it might prove difficult to fix even with the schematic.
You have 3 voltages in that thing and one is High voltage for the Valve.
So be very careful as even 150 Volts can kill you.
You really need to establish those psu voltages and find all the points they travel too.