Winfow part, not sure how to get out of frame

Hi there! Looks like you have a pivot shoe. There are a few different methods of removal, and we go over each one in the following two videos. I highly recommend watching them to learn how to remove yours from the track.

Once you have your pivot shoe out, I would then compare it to our 15-129 to see how well our dimensions match up with your own. I think this is our most promising match.