The final tetrode stage may have an error:
Although the sopht schematic shows it differently I believe that (typically) when tubes are depicted the grid order (from bottom to top) is following:
(control) grid (where signal goes), screen grid (tetrodes), suppressor grid (pentodes), and so on for other tubes.
See...
Tetrode:

Pentode:

If that is the case as well in the site showing the 12AL8 pinout (those pics are poor) then you should switch order of the pins 3 and 2. I'm not saying you have it wrong now - I'm just saying there is a possibility for that and you should check it out.