Tzemach Atlas links to a post on CrownHeights.info that contains links to audio files of a farbrengen (informal talk within a hasidic gathering) given by the titular head of worldwide Chabad, Rabbi Yehuda Krinsky. In this talk Rabbi Krinsky admits the Rebbe's sister-in-law, the eldest daughter of the sixth rebbe, was beaten and blinded by a Lubavitcher rabbinical student (second audio file about 1/3 of the way in), admits that Chabad did everything in its power to stop the Rebbe from being deposed by a New York court regarding his incitement of that incident, and frequently refers to the grandson of the sixth Lubavitcher rebbe, Barry Gourary, as the "sitra achra."
For those who do not know, "sitra achra" is a kabbalist term that denotes the evil "force" opposite the goodly "force" of God's will. In hasidic street usage, "sitra achra" would be the equivalent of the devil and its opposite would be God. (In truth, the evil "force" is controlled by God, too – it is what allows us to have freedom of choice by choosing good over evil.) While unspoken, the problem is Rabbi Krinsky uses the term in a way that shows the polarity is different here: Barry Gourary is the devil and the Rebbe is God.
Rabbi Krinsky also admits that the oldest son-in-law of the sixth rebbe, known as the Rashag, was often ridiculed by Lubavitcher rabbinical students – including Rabbi Krinsky – during the early years of the Rebbe's leadership. As I saw personally, this continued into the 1980's.
It also should be noted that the sixth rebbe's library, the source of the dispute that led to the beating, contains many interesting secular books collected personally by the sixth rebbe beginning when he was still a child. Included were editions of Sherlock Holmes in Yiddish and other works of fiction. Chabad, despite what Rabbi Krinsky says on the audio files, could not go to an independent beit din (religious court), because no independent beit din would have awarded the library to them. The secular court was untroubled by the normative Jewish law regarding inheritance, and by the presence of secular books – which by the estimates I've seen made up a large part of the collection. A beit din would have awarded those books – all of them – to the surviving male heir, the sixth rebbe's grandson, Barry Gourary. And so, Chabad did what haredim so often do – whatever was most convenient.