Jayco - Lippert experience
I own a 2018 Whitehawk and had a similar experience, the shackles that anchor the leaf springs, one broke the weld to the frame. Warranty was done, i called Jayco and they reffered me to Lippert. Lippert efficiently handled the repair and picked up the tab. They sent me the replacement shackle, i located a welder locally and provided the contact info to Lippert. They paid the bill and i was back on the road in 3 weeks.
I was skeptical of how it would go, but wound up very pleased.
Give it a shot.