Water Ingress to sliding door black trim

Hi. I am a first time poster. I have very recently bought an Autosleeper Symbol 'Y'reg. Yesterday it was not raining (at last) and I noticed water dripping from behind the sliding door black plastic trim panel. The water was dripping down the outside of the door from the right hand lower corner. There is no evidence of water entering inside the van. I guess that the trim sealant is damaged. What should I do?
A. Ignore it as it is dripping down the exterior of the van? 
B. reapply new sealant along the exterior edge of the trim and what sealant would you recommend? 
C. Remove the black trim (and I guess the sliding door window which is part of the trim), check what damage has perhaps occurred if this has been going on for a while, and put the trim back and reseal?

If you recommend C. is removing the black plastic trim (with window) a simple job of unscrewing the obvious, visible, screws in the black trim on the sliding door exterior? I do not want to make it worse and am not the greatest handyman (just ask my wife!)[You must be registered and logged in to see this link.]

[You must be registered and logged in to see this link.]
Hi ,fatherglyn
t,his was behind the plastic panel on the off side of my van .

The inside blinds and plastic surround has to be removed then there is a wooden surround covered in chord carpet held on by screws use a strong magnet to try and locate and unscrew and  underneath another wooden surround if that s dry you should be ok ..around the wood has screws and clips  holding the window in place along with mastic . bit of a job to remove without breaking anything . Or just try Captain Tollys creaping crack cure around the window to trim and also around the plastic to door join dribbling from the top to run around the joins ,mind your paint work as it does run .

Have fun

Thank you - will try sealant first!!!!!