X2 - Contact Jayco, and have them contact Dexter. But I would seriously be considering requesting a complete new axle assembly and tires. Those tires have taken a beating, and are probably showing some very bad wear
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Does this axle requiring standard tapered roller bearings or are they using one of their other bearing setups? A coworker just replaced his bearings in his 5th wheel (2 yrs old, different brand, with Dexter axles), after one bearing failed while on the road (mile from home). If I recall correctly there were no tapered bearings at all, but some kind of needle bearing that is installed with one large nut (not a castle nut) that required extremely high torque loading force (300+ ft/lbs??). Needle bearings do not take side loading very well, and are notorious to fail at a young life.
Best of luck, keep us updated.