[beery]

Hi Doug,
If you are able to rotate the scan coils (you may need to loosen the clamping screws) a bit then you can see if that also rotates the focus errors. If the focus errors rotate with the coils then that would indicate that the scanning yoke could be magnetised or that the yoke is not properly centred on the scan coil windings.
If the focus errors do not rotate then it could be down to the alignment of the electron gun alignment.

My limited experience of viewing these sets is that the focus is not as good as with a magnetically focused crt.
I've not played with the controls myself though, but I assume the set's I have been set up for optimum average focus across the screen.
I can tell you that the CRT used in thec15" Baird T5, which is also from 1936, gives a much sharper picture and I'm sure this is down to the CRT design rather than anything else. The 15MW2 crt used in the T5 is a simple directly heated triode tube with magnetic focus.

Cheers
Andy