[Marches Farmer]

I generally check out a ewe that's been seriously pushing for 20 minutes, or if I can see only one foot.  If you go in early enough the head will often still be far enough back to make it easy to just push the lamb back a little, enough to feel across the chest and find the foot that's folded back, cup it in your palm and gently draw it forward.  Once all's in place I generally leave the ewe to do the last few contractions, unless I can see she's getting very tired.