With your having problems with both of the systems installed in your trailer, I would suggest switching brands. I know it's no help with your problem now, but if you just get another linear, you might just have problems again and still be dissatisfied.
2012 GMC 2500HD D/A Crewcab
2012 Jayco Eagle SuperLite HT 26.5 RLS
2009 Crestliner Superhawk 1900
2013 Polaris Sportsman 550 EXP
2008 Polaris Sportsman 700 X2