Do you have this shoe
I don't believe this is the 15-178, the design of the plastic is too different. Unfortunately, it's not possible to identify what you have fully while it's still in the track. Too much is obscured.
This service requires clear and unobstructed pictures of all parts you want to replace so that we can more effectively find a match. Your next step should be to remove the shoe from the window and show us a photo of it by itself. We also need you to measure its width and thickness.
Please ensure all dimensions are written out in your response. A photo of a tape measure is not sufficient.
Once we have that data, we will check our inventory for a match.