I thought I would share this here given that my experience is probably not unique.
We are starting our 3rd season with our 325RES and still enjoy it very much.
When looking over our rig, I noticed messy corners on the upper slide room 'flanges' when extended. The mess is also winding up on the outer seals against the outside walls, and along the top edge of the slide, as can be seen in the pic.
Investigating further, I found that that the sealing material used in the corners is moving around with the flexing of the trailer most likely when deploying the slides, or even flexing going down the road. I believe this material is 'Eternabond', which is a tough white vinyl membrane backed with a VERY sticky gray material. You can see this sealing moving around and bunching up in the first pic. When the sticky grey stuff gets exposed, it sticks to anything it touches, and these areas were starting to get quite messy looking.
Also on the first pic you can see that the sharp cut edges of the mouldings are actually cutting the seal.
I decided to remove the eternabond and clean up all of the gray stuff which revealed nice clean looking corners. This stuff is tenacious! You will need to use some kind of solvent, and plenty of paper towels. I also used a toothbrush. You can also see the sharp edges of the cut flange in the second pic.
After cleaning this up is looks to me that the application of this stuff was somewhat overkill, which is counter-intuitive for the RV industry for most of us.
I've filed the sharp edges smooth and sealed the joints with some good Geocel Proflex sealant. As you can see, the flanges themselves have some good sealant in the joint, so no worries there. I did this for the 4 top corners of the atrium slide and kitchen slide. The Schwintek bedroom slide corners (factory prepared the same way) look quite good yet, so it appears that this room doesn't flex like the other two larger rooms.
This cleaned it up a lot IMO, and it was just a matter of time before the factory job simply failed.
I'm sure fellow Crusader owners will see the same on your rigs, and there's no telling how many other FR products use the same sealing techniques.