IMO the compromised slide roof trim sealer tape should be removed and replaced. Also, not a good application for a Dicor patch-fix due to the location (horizontal wiper seal contact).
I wouldn't recommend adding a 2nd layer of tape because Jayco normally uses a thin sub-grade sealer tape covering these slide roof trim applications and degrades rapidly (unlike Eternabond sealer tape). I've seen new 2018 Jayco units on dealer lots with the tape already pulling away from the slide roof EPDM surface.
My prior 2005 Eagle I replaced the OEM slide roof tape after 6 years with Eternabond sealer tape (screw heads starting to work through) and that was back when Jayco used a better grade of tape. My new 2018 Jay Flight I went ahead and applied Eternabond to the slide roof trim..., and ran a bead of Dicor along the edge of the tape that backs up to the 4" slide flange.
Bob
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2016 GM 2500HD 6.0L/4.10
2018 Jay Flight 24RBS
2002 GM 2500HD 6.0L/4:10 (retired)
2005 Jayco Eagle 278FBS (retired)
1999 Jayco Eagle 246FB (retired)
Reese HP Dual Cam (Strait-Line)