Well, define your 'many'. The HRE had coups, especially during Henry IV's reign. First coup happened to him in his early teens when the archbishop of Cologne, Anno, abducted him, because the 'constitution' of the HRE said that the regent is the bishop in whose domain the underage king resides. Even after Henry's coronation coups happened, during the Saxon Wars, the Investiture Controversy and even one of his own sons tried to replace him.