I replaced the bedroom and full slide topper using Tough Top Awnings
The replacement topper material from Tough Top Awnings to me is a better material than the original.
RVgeeks has a video on youtube describing how to replace the toppers. The bedroom topper was easy. The full wall topper on the driver's side was harder since it's soo long. Takes 2 people.
I noticed we have the same Ventana model. I attached the service manual for the full wall slide. Describes how to remove the slide cover. Use silicon as it helps "rusty/stuck" pins & connectors move. I also used silicon when inserting the new slide topper to help it slide into place.