A few questions and comments;
Have you determined if the outfeed table of your jointer is on the
same plane as the blades of your cutterhead? If so, when you push
stock across the table do you always push with pressure over the
infeed table? I use a little infeed table pressure to get started and
then try to use only outfeed table pressure and pushing from the back
side. This way I won't cause the board to dip down at the rear as I
cross the cutters.
If the blades are not in the same plane as the outfeed table you must
align them by adjusting the table (if possible) or resetting the
With regard to Yellow Pine, it will be harder to drill and screw than
white pine or poplar but it should machine up well with any decent
power tool and a good blade.
Are you building a full size mock-up? What are you making?