check the wiper seal on top of the slide. it should wipe all the water on top when pulling it in.
also check around the outside frame of the slide, when closed.
this was one reason we bought a slidetopper.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC