Often when I find a school of crappie on piece of brush on a steep break, they will often be off the deep side hanging off the cover. At least that is my majority of experience on Kentucky Lake. Sometimes they are on top of the cover and a straight retrieve works well. But when they drop off the deep side of a piece of cover, it can be hard to come over the top of cover and then get down into the school. I usually accomplish this by tight lining the jig and plastic down over the cover and let it continue to fall next to the cover out into deeper water. So it is working back to me but also falling deeper as it goes.
The key is to position your boat in deeper water or basically cast shallower and let it pendulum out into deeper water. Recently that has been working well for me as the crappie are still pretty deep on cover and down around the bass on the break. I like the lightest jighead I can get away with because you might catch the top of the cover and you can use another retrieve — the pull — to get your jig over and then tightline down through the fish.
A heavier jig hangs more. Just a fact of fishing around wood cover.