After re-reading your post, Dave I sure agree with Eagle 5. Use a long level or just a long straight edge and see if is just the bulb seal retainer piece that is bowed. From your description it sounds like it is (see the pic with the arrow; may need to double click it to enlarge)..... and just at the front edge of the slide, not the rear edge, I take it. I can't envision how that could happen unless something was in the way right there at the edge when the slide was closed.
The vinyl trim strip in the other pic is only there to cover the mounting screws for that bulb seal retainer piece .... like in other areas on the MH. It has a retaining screw at the bottom, but if you remove it, you can easily peel out the vinyl strip (and replace it later) to gain access to the screws. Hopefully the bulb seal retainer is "staightenable" if that is indeed the problem.
If you haven't used it yet, here is the site for WBGO Manuals and Dwgs.
https://winnebagoind.com/resources/manuals/
Using the above link, I looked at the parts catalog for you coach. The slide parts are shown on pg 80-83 or so.......but it doesn't show that bulb seal retainer. :^(
http://www.winnebagoind.com/service/...08/8wf331c.pdf
A call to the Lichtsinn RV parts dept (lichtsinn.com) will tell you if that part is available or not. Hope it is.
Sure sounds like "hidden damage" on the part of the seller. Bummer.
Good luck with the fix. Let us all know how it turns out; we're all still learnin'.