We used a JD 31 conditioner for many years. Helped get the hay dry the day or so sooner that people claim. The SOB would also plug if the hay was at all wilted. Since we mowed with a JD 9W and had only one tractor, we lived with it. The day came we fertilized the hay and then it couldn't handle it at all. We threw in the towel, got a mower conditioner and after we got that running right, wondered why in heck we waited so long to make the step up.
Most conditioners have provision to release spring pressure on those rolls. There's a reason for that. Real fun when it's 90 out and you want to get something done.