If you do a search about this here or on the Vmag site you will see this is one of the most commom problems a VX has, you will also see there are many different ways to solve it. Mine was new, and was delivered this way. I don't quite know how the warranty is for the second owner, but if you can, get Isuzu to pay for it. Have a dealer order the part, and then wait while they fix it. That's what I did, and while it was a hassle that's what the warranty's there for. As far as I know, I don't think anyone here has has ever been denied this repair under warranty, but I could be wrong.

By the way that weatherstripping/trim is important, and not just for cosmetics. Use the search feature (if the problem hasn't been addressed here, it's definitely on Vmag - many times), the info will be very helpful if you have to, or decide to, fix it on your own.