I've bought a lot of window channel looking for something that fits well and finally found a solution - - channel for a Ferrari Boxer... it requires very minor trimming on the top edge but is dimensionally identical to the Goose material.
Photo shows 3 trimmed strips and 1 untrimmed strip to highlight the diff. Easy trim job with scissors. Once trimmed it stays in place with no adhesive tho I may use a small amount for the final install.
See Cigognani's website, part #16323926. Only down side is their high shipping cost$ so I make infrequent larger orders from them & spread the pain. For small purchases one of the US resellers would probably be best.
Any other good options for this troublesome part?!! Regard, Nate