I had the same trouble with the ring not being able to tighten. Forest River replaced the whole power cable under warranty. The replacement cable was black and 5' shorter.
I was able to remove the over sized ring from the original yellow cable, purchased a yellow cover and ring from camping world. The yellow cover was very easy to remove from the black ring from Camping World. With some elbow grease, screw driver blade, I was able to remove the ring from the orignal yellow cable, replaced it with the ring from camping world. It now fits tight onto the fitting on my RV>
Sid, Lois & HRH MISSY Terrible 2s SHIH TZU
2011 ROCKWOOD 8285 WS
2014 F-250 KING RANCH PS/SD/6R140/BFT
BOLIY PRO 3600SI GEN
DAYS CAMPED 2016 57 DAYS