May we see it. There's not much that can be said without a video.
My form is absolute crap. Right now I can blunder through a set of 5 at 280 lbs. What I'm thinking I am going to do is break out the book, drop my weight by at least 50% and start working my way back up only when I'm completing sets of 5 with acceptable form. Any advice is appreciated. As near as I figure my cardinal sin is a rounded back mid-lift.
May we see it. There's not much that can be said without a video.
So do another set and film it again.
While you think your form might be really egregious, it might not be all that bad. Basically, you may not need to do a 50% reset - it depends on what could be improved. It is tough to say without being able to see. You might be able to drop 50lbs and reset, maybe none.