I'm thinking right now... How did Bishop Fellay become Superior again?
I think it was a) because of his people skills and b) because of his mastery of 5 European languages. The Chapter that elected him doubtless did not realize how he was going to change.
Unfortunately, since most SSPX Chapter members become Chapter members by virtue of the posts that they occupy, the Superior General - who decides what priest to put in which post - chooses in practice the majority of the Chapter members. Right?
So if the Superior General decides that he wants to stay in office a second time around, he picks the priests who he knows are likely to vote for him. Right?
Also, if the Superior General wants a certain Liberal mentality to prevail in his society, all he has to do is pick chapter members with that Liberal mentality. If he wants a certain decision to be "made by the Chapter," he just has to pick the priests who will go along with whatever he says is the right decision. This means that even if major decisions are supposedly "made by the Chapter," in practice they are all made by the Superior General!
The conclusion is that the Society could only survive as long as the Superior General was solid. As soon as a Superior General came along who was a bad apple, the Society was bound to succumb.