Jayco uses different window suppliers...., one of them is "Cleer Vision Windows" (CVW) and you will find their name on the window glass (corner of).
The vertical wiper seal in slider windows is attached to the center metal mullion and is replaceable without disassembling or removing the window. These wiper seals have a tendency to shrink
and create gaps for moisture intrusion.
The wiper seal in question comes in contact with the sliding window during open/close operation....., and I presently have my TT in for replacement of all wiper seals due to shrinkage 'gaps' (warranty claim).
The following CVW video provides the wiper seal part number and simple R&R instructions.
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)