Removed these the other day and had the same problem with them just spinning forever. Eventually I resorted to some needlenose pliers to mangle the one on the left enough to pull it out without putting too much pressure on the ducting itself. That allows you to pull the duct to the left off and access the inside of the central duct, then I was able to use a long flathead screwdriver pressing on the back of the two on the right while pulling gently with the needlenose pliers. In the moment I couldn't think of any other way to get them out and while one ended up being unusable, I figured it was better than breaking the ducting itself. Thanks to 2mbb for posting the P/N, I did a quick search the other day and had no idea how to find replacements.