Having an issue with my new vibrochamp build. The intensity pot works fine although i could not find a 25k reverse log pot so I used a 50k linear pot with a 48k resistor across wiper and top. However I have no speed control at all. I have swapped tubes and also disconected and measured the 3meg reverse log pot and it functions as normal. What components should I check first? hopefully something will jump out in these pictures.