I had this exact same problem on my Designer. The left rear adjuster mechanism was not in the wheel. I posted all of my detail here at the time. It was in June-July 2012 and was one month prior to my warranty expiring. I was away from my selling dealer and had a remote RV repair guy perform the repair. Dexter paid it all no question. I did report to my selling dealer who notified Jayco who notified Dexter. They never even questioned the need for the remote repair guy. I did report I was major concerned about towing with 25% of my trailer brakes not working and with 2/3 of what I did have on one side.
Look at my previous threads and you should find all of the detail.
2006 GMC 2500HD CCSB 4x4 Duramax/Allison, Titan 52 gallon fuel tank, Prodigy Controller, B&W Companion Hitch
2010 Jayco Designer 35RLTS, Cummins/Onan RV QG 5500 EVAP, Progressive Industries EMS-PT50X, TST Systems 507 TPMS, RV Flex Armor Roof