Polaris stuck on front wheel

Hey guys! First time poster here. I've read a bunch of posts but can't seem to find my exact question (or answer!).

I have a 30,000 g pool. I have a polaris 180 or 280 (I'm not sure exactly) pool cleaner. The white plastic screw that holds the front wheel in place broke the other day so I ordered a replacement online and put it back in. The wheel turns great, just like the back wheel. However, now the polaris only rides on its front wheel, tilted up. I'm not sure if it was just a coincidence that the front wheel screw broke or not, but from what I've read this might indicate an issue with the white head float or the back up valve?

What troubleshooting tips should I try next?

Thanks for your help in advanced!