Juggernaut is an Avatar of Cytorak. you can shut him down with mental attacks but that is about it. if Cosmic Spidey punched a hole in Juggernauts head, the power of Cytorak would just fix it and Juggernaut would be back again. the only way to kill Juggernaut is to kill Cytorak first, then kill Marko.
Juggernaut said it before "knock me down 100 times and I'll get up the 101st just as fresh as ever"