Ella EL34 Bias Help

[plepagejp]

I have posted this message on their forum as well but thought the more brains I could get involved the better chance of working it out. This is my first kit so I have no experience with faultfinding...
After finishing all of the wiring I started to take measurements but I can only get the bias down to 0.4 VDC on one tube...

I resoldered the Bias Pot PCB just to be sure. When checking the VDC at pin 5 I get a variation from -29.5 with the bias pot turned fully counter clockwise to -63 VDC with it turned fully clockwise. I changed all the settings to -50 VDC as per manual.
The voltage readings between pins 2 and 7 on all the EL34 sockets are 6.05VAC. The middle four measure at about 5.8 VAC. I don't know if this is low but it may reflect the transformer being wired at 110 and my 100 volt power here in Japan. The B+ voltage at the PS PCB is 421 VDC.

With the four EL34 tubes inserted;
Socket A: 0.8 VDC fully counter clockwise
Socket B: 1.1 VDC fully counter clockwise.
Socket C: 0.4 VDC
Socket D: 0.8 fully counter clockwise
After receiving some advice advice I decided to change the tubes around and try other ground points.
Socket A / Tube D: 0.8 VDC fully counter clockwise
Socket B / Tube C: 0.4 VDC
Socket C / Tube B: 1.2 VDC fully counter clockwise
Socket D / Tube A: 0.8 VDC fully counter clockwise
The different ground points don't seem to make any difference to my readings. I tried the IEC ground, negative RCA and the grounds between the 10 ohm resistors at the sockets. From what I can see the problem seems to follow the tubes? Could they be faulty? I have one that seems fine, two that are double what I need and one that is almost three times the required voltage. I don't really want to start a complete rewire if it is unneccessary...
This about all I can think of by myself. Does anyone know what might be causing this so I can work out how to fix it?