I have a 2016 27n and have the same problem.
Most of the trim around the slide will come off. I am planning to repaint them and then reinstall. That have some paints designed for plastic. I don't know if it will hold up or not.
Good luck with yours
2016 Itasca Sunstar LX 27n, unattractive brownish hue. 530 Watts roof mounted solar, 165 Watts portable solar, Winegard G2 Sat Antenna, Progressive Industries Surge Protector, TPMS, Sirius Satellite Radio.