Update: I emailed Summit about this problem. Two hours later, this is the response I got back:

" This sound could possibly be associated with a joint in the platform that
has some slight movement.

It is our policy to replace your treestand.

We will send a new stand and a pre paid fed ex call tag. Please place the
old stand in the new stand' s box and return it by using the fed ex label."

That is just downright incredible. It' s even more incredible that Summit responded to an email so quickly. Right now I am dumbfounded. How can you possibly top that kind of service?!