Yes, there have unfortunately been SSPX priests accused of and guilty of child abuse. Fr. Carlos Urrutigoity and Fr. Benedict Van Der Putten immediately come to mind.
Although these two priests left the SSPX of their own will, they were nonetheless ordained in SSPX seminaries.
Here is the case of Fr. Carlos Urrutigoity, who was a former professor at the seminary in Winona, albeit briefly, during the good years when Bishop Williamson was rector:
http://jloughnan.tripod.com/urrutig.htm On Fr. Benedict Van Der Putten:
" I once knew an SSPX priest, Fr. Benedict Vander Putten, who I thought was on fire with the love of God. Turns out he was on fire for the love of underaged girls. Need I go on?"
http://webcache.googleusercontent.com/search?q=cache:GRqRD2OEgmYJ:arturovasquez.wordpress.com/2009/10/12/archbishop-weakland-the-after-article/+fr.+benedict+van+der+putten&cd=5&hl=en&ct=clnk&gl=usFather Benedict Van Der Putten
San Francisco Faith
November, 2005
FATHER BENEDICT VAN DER PUTTEN, a priest formerly of the Society of St. Pius X, has been relieved of his faculties by Pope Benedict XVI, according to an announcement issued by the chancellor of the diocese of Marquette in August. Van der Putten, who, beginning in 1995, had been retreat master at the society's St. Aloysius Retreat House in Los Gatos, left the Society of St. Pius X in 2000 to seek reconciliation with Rome. In December 2003, the bishop of Scranton, Pennsylvania, where Van der Putten had gone to seek regularization, announced that he had refused incardination to Van der Putten "because of the seriousness of his admitted sɛҳuąƖ misconduct." According to the diocese of Marquette, Van der Putten, "at one time a holder of a celebret from the Pontifical Commission Ecclesia Dei, has been dismissed from the clerical state by decree of His Holiness, Pope Benedict XVI after being accused of sɛҳuąƖ abuse of minors." Van der Putten reportedly is currently living in Hawaii.
http://www.bishop-accountability.org/news13/2005_11_SanFranciscoFaith_FatherBenedict_Benedict_VanDerPutten_1.htmRegrettably, no Traditionalist group has been immune from the scourge of the accusations of child abuse, whether they be Ecclesia Dei, SSPX, or Sedevecantist.
It is a problem after all that St. Peter Damian faced during the 1000s.
Nonetheless, the SSPX is superior than any other Catholic organization in cracking down on perverse priests, as they tried to warn the diocese of Fr. Carlos Urrutigoity.