Sheet tin and rivits?

Hmm, could you be a little more specific please? I am thinking it might be something else. I was looking again at the photo. See the upper right corner? There appears to be the same yellow looking substance that may have flowed down onto the hub. Maybe someone had something that spilled and never cleaned causing this. The previous owner did have small children and one around the age of spilling and hiding. I remember how my mother found the oatmeal I hid in a dish cloth inside the china cabinet after it began to stink up the house when I was very young or maybe one of the parents spills something but did not realize how far it spill or forgot to clean it (check see how far it went)?