Find out who manufactures your motor, Lippert etc. and contact their support center directly. The warranty is most likely through them rather than Forest River. Warranties on RV's are not like those on cars. Each component is warranted by its manufacture rather than the RV manufacture itself. I had the same issue on brake components on my 5'er. Contacted Lippert directly who resolved it quickly. Not sure why they were not getting back to my dealer promptly.
2014 Winnebago 26FWRKS 5th Wheel
2007.5 Dodge 2500 6.7L Diesel
2004 Dodge Durango Hemi 3.55 (Used to tow TT)