Bias adjustement pots.

What is the best way to check the correct performance of the potentiometer(s)?
848a036e efd3 4d69 a7de 31c247c14aadmarakanetz
See the article by Dejan V. Veselinovic
appreciate for interesting article!

less-likely the DC-component may be from the tube amps due to the damaged trim pot since they have an output transformer.
on the other hand I can test the quiescent output directly before the transformer and see if it's present there.