Thank you Jack for the speed response. The pictures of the metal plates for the cable to hold the cable from cutting into the structure at the bottom of the upper wall really help, and I think I can manufacture something like that for mine. I will also check my other there cable ends to see how they are mounted.
However, as I said, my left front corner has significant rot in that lower structural beam that runs above the fiberglass sheet along this lower edge. If there was a plate there originally, it is completely non existent and the cable is cutting into the structure. I am going to attempt to attach a photo to this thread so you can see it.
HiLo damage 2.jpg
HiLo damage 1.jpg
It seems to me that it's going to be easiest to tear into this section with the top in the raised position, but I know I'll have to disengage this cable to remove the sheeting to get to the rot.
Therefore, my questions remain - do I do this with the top raised, and, if I do, am I going to get into trouble by unscrewing the cable from its connection? I plan to use some jacking device to keep the corner from dropping while I repair it. I'd also like to know, if anyone has this experience, is it better to get to the structure inside the wall by peeling the sheeting off the outside, or the inside.
Thanks again for any and all help.