I ran into the same problem when my hen hatched out 9 chicks. She kept them in a dog kennel the first few weeks but then wanted to take them back to her original coop. The ramp was just too steep for her and didn't have the room to make it longer. So I took a cinder block and put it underneath the bottom part of the ramp. That made the bottom higher and in turn lessen the "steepness" if the ramp. They easily could do it then.
I hope that makes sense?
I hope that makes sense?