Here is a Marvel Girl KO scene from X-Men, Volume 1, Issue #43 (Marvel, April 1968) -- she gets KOed and captured, along with her teammates. The final KO itself (where she and all the other X-Men are zapped) is not that great, but there are some sexy scenes leading up to that, as she is getting battered senseless by Magneto's powers. The scenes that follow show the sexy redhead unconscious and in bondage.
Also of note -- this is the first appearance of that tiny green minidress that Jean filled out so well.
Source: my collection