Clearing a Six Lug Timpano
For clearing a timpano with six lugs, the same eight lug theory applies, but instead of two quadrants, it is sometimes easier to conceptual three quadrants where one pair of diametric lugs has now has four orthogonal lugs (90º) aka secondary channels to contend with instead of two. You still have primary and secondary channels, but the secondary channels have four lugs that control the balance of the tension instead of only two. It is all because of the double degeneracy of the principal tone.
In a nut shell, when adjusting diametric lugs 1 & 2, in order to balance the orthogonal degenerate, you also need to balance 6 & 4, as well as 3 & 5 since the orthogonal falls between these lugs.
Likewise when you adjust diametric lugs 3 & 4, you will also need to adjust 6 & 1 and 5 & 2.
For diametric lugs 5 & 6, you will need to adjust 4 & 2 and 1 & 3.
When listening for pitch fluctuations in the secondary channel(s) just be more cognizant that it could be anyone of four that is the culprit.
It really is nothing more than a balancing act with regard to even tensioning of the head. If you can get the tension pretty close at each lug with a Drumdial or something similar, tweaking and fine tuning the overall pitch becomes less of a challenge.
