sika aktivator is "painted" on the door where the glass will be stuck on.... clean off as much old glue as practical and use aktivator over it and the paint..... BE CAREFUL aktivator is not meant to be removable.
sika flex "255" or preferably "256" or "sikaflex Move transportation" are the correct glues (move transportation allows for damage to the door panel.
apply glue with a nozzle cut with a tall V notch removed, about 1/4inch at end of nozzle and 1/2inch to point.... "more" glue does NOT make it stronger.
After sticking, allow AT LEAST an hour before moving.... 24hrs is best...... SLAM ANY DOOR and it will BLOW the glass OFF, until its hardened enough.
do it OUT OF the rain..... DAMP days are best (it uses atmospheric moisture as a hardener)
old adhesive is best removed with a warm (hot but not too hot) knife or thin wire
malcolm