I found that the crates "look" like they are lined up next to the two stacked ones but really aren't. That was where I had problems till I figured out I needed to move them all the way to the right and then up one next to the two stacked crates (there are actually two spaces below the stacked crate but it isn't all that obvious). All along I thought I was right next to them and the view made me think I was correct but when I jumped over I still couldn't cut the chains. The perspective here is tricky but once I figured it out voila!
"Face it, I'm older and I have more insurance!" Evelyn Couch 'Fried Green Tomatoes'