You're on the right track - do the fluid analysis and call Cummins back - they're very good about providing recommendations based on the info you give them. Try to figure out if the fluid is the original 2008 or later - that will help with their recommendations. When all said and done, if they recommend a flush and replacement, on a 10 year fluid - that's not a bad idea. If that fluid doesn't do its job you're in for a very expensive repair ...
2015 Itasca Ellipse | 2014 Jeep Grand Cherokee