The MV pot halves are grounded correctly in the second picture.
However, the bias supply is still connected in the wrong place. The bias supply is connected to the two 100K resistors, which connect the bias supply to the two sides of the signal path, at the junction between the second coupling cap and the 1K5 resistor (on each side).
Take a look at this schematic...
http://www.lynx.bc.ca/~jc/73_JoePiazza_YGM34.gif
....notice how the bias supply is connected to the 6BQ5 output tube grids through the two 100K resistors. That should get you in the right ballpark.