To avoid the crop or leakage from anywhere else, I started using small (6 inch) ceramic knives for the detailed work.
We "do the deed" up high on the neck, while they're in a cone. After they're scalded/plucked and it's time to process them down, I take the head off from the upper part of the neck, where I then have the long wind pipe and the tube thing that goes to the crop intact. I separate those, peel back the (crop pipe? esophagus? what's it called?) so that I can tie a knot in the one that goes to the crop. Then I work at loosening the crop from the membranes and tissue holding it in there, then I remove the neck as low down as I can.
Then I take the feet off, bending the leg back to tighten the tendons, cutting through the joint easily.
Then I move to the back end, positioning the bird breast down. I take the tail off behind the oil gland, cutting down and away from the body at a 45 degree angle, so that the knife finds the spot where there isn't a vertebrae and it goes through easily. Carefully stopping before hitting the poop chute. I turn the bird over on it's back, pinch up the skin about an inch below where the keel bone ends, and go straight in with the knife until I get through the membrane inside. Then I cut down, towards the side of the vent. If I had cat through the tail far enough, those two cuts meet up and I only need to do the other side, careful not to cut the poop chute. Once I have the vent/tail loose, I reach inside and start loosening things up, searching for the gizzard.
Once I have the gizzard in my hand, I pull with even and straight pressure and if I had loosened the crop enough from the front, it comes with in one motion. Liver, spleen, intestines, crop and gizzard come out in that pile. Then I go back in for the heart, lungs, perhaps a kidney, testes if male, and that windpipe.
We keep a hose handy at the processing table, so that we can rinse as needed and then rinse thoroughly prior to putting them into a salted ice bath.
I've done so many now that I could almost do it in my sleep.
