Replacing Foam in Tri Fold Sofa

[ftrupe]

I have a Passport 23RB with a Broyhill (I think) tri fold sofa. The cushion that you sit is on is in need of replacement foam. It doesn't appear that there are any zippers or easy way to do this. I watched a Lippert video, but it didn't seem that they were putting new foam where you would sit. Any ideas would be appreciated.

Thanks