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I have an issue with the vibrato circuit on my recent 5f11 build.
I have done much research/experimentation but to no avail so I am at wits end and need help.

First, the amp works fine and sounds great.
The depth control works and sounds ridiculously good (bias resistor set to 34 ohms) but only at precisely 11½ on the dial. Anywhere else, nothing.
The speed control seems to work fine.

Other facts (that may or may not be relevant):
B+ is 345V. Close to the specified 340V
PT is a Hammond 290CAX,275-0-275. Power is taken from pin 4 (or 6) with 100K range resistor in the bias circuit.
The voltage drop across the 470 ohm resistor at the B+ should be around 10V. It is actually only 2V (at any B+ voltage).
Pin 1 on V1 should be 160V it is 174V.
Pin 6 on V1 should be 155V it is 177V.
The two 220K resistors at the inlet to the power tubes are measured at 218K and 226K.
The foot switch affects the vibrato function; that is when it is plugged in it kills the depth, it does correctly turn the effect on/off though.

I blew out (since replaced) the 470 ohm resistor when I connected the B+ to pin 6 on the 5Y3. (maybe that did it!)
I have triple and quadruple checked everything!
I think it is either grounding or, a bad cap. However, ‘ I know nothing ’. Evidently.
Any ideas/advice at all would be greatly appreciated.
Here is the schematic: