We tip them up on there side and follow the wet foam into the leak. Alot of times you can follow it with your hands through the first layer and then a putty knife or we use sawzall blades taped to wooded handles of vaying lenghts. Most times it is very easy to find the leak by following wet foam and the culprit is usualy at a jet or a manifold which is just a few inches to 6 into the foam. Only remove the foam that needs to be removed, but don't be afraid to remove to much to facilitate the repair as it is easy to replace.
