I put a 4 inch paver under the end. I am hopeful. I may swap it with an 8 inch cinder block. The leaf left piled in the run is about 4 inches thick anyway, so the 4 inch paver just lifts the end of the ramp to the height of the leaf litter. It did help the angle a bit. I will go higher if this doesn't work. The other thought is that they are just scared to go through the smaller doorway - it is about 7 inches wide and 10-12 inches tall - my biggest girls fit so they all can fit, but I think these gir lo s are be scaredy cats. The speckled sussex, Bear, went in on her own yesterday so that is one more who figured it out. 3 more to go.Decreasing the angle I think will solve the problem. They can jump up onto the lower part of the ramp with no problems. I don't think the the slats are problem.
Not sure how high you need to raise the lower end, but an 8" cinder block works well.