If you read the Nissan factory service manual it says calls for some points to need sealant. I had a friend with a 620 who had a new Precision brand seal with the same prob. With the help of a glass professional they R&R’d the windshield 6-7 times trying to get the seal to fit w/o sealant. They were scraping rust, painting, bending metal, etc. They never got it to seal. I informed them about the service manual note. They sealed it, no prob. They surmised the cab may have been a bit tweeked from a PO fender bender. Hope this helps?