Cracking sealant definitely needs to be addressed. Not sure if you're talking about a sealant or the butyl tape that squishes out a little when they screw the corner mouldings on. What I did on my father in law's Jayco, is cut back as much of the gray butyl putty, and seal the areas with Geocel Proflex. That is some very good sealant. It comes in white, clear and black. Maybe gray also but can't remember. Usually can be bought at any camper place, camping world, or a scad of places online. Not cheap, but I've never had to "redo" any of the proflex. I always masked off a straight line where I wanting the bead just to make it look neat. I just finished adding some and redoing some of the factories sealant on our new fifth wheel with 4 tubes of the proflex. I'm particular about this stuff and have yet to see a factory job that I liked. If you have any pictures, might help diagnose a little better. Should be able to take care of every seam on your Coachmen with dicor self leveling lap sealant on the roof, and proflex on the sides.
John and Rebecca Dickson
Emma-7 / Little John-5 / Iva-1
Full Timing Again, Rev B
2013 Ford F-350 Lariat CC LB PSD
2015 SOB TT - With OC's Awning Poles (#8)
At least in Heaven, RVs will be perfect, and I won't have to keep fixing them.