Rubber molding on F355 door frame

The little triangular rubber molding fell off my F355B for the second time. It's the one that is at the back of the passenger window near the door lock. I am trying to reglue it again with 3M weatherstrip adhesive. Having trouble getting it to fit it just right. Do these things shrink significantly after 15 years? Would a new one fit/attach easier? It's a piece of rubber not more than two and a half inches long. I assume a new one is $500. Any advice as always is appreciated.