Close but doesn't fit

I purchased the 15-004 Channel Balance Shoe, Winged, but there is a lip on the part I received that my old part does not have. I tried modifying two of them, which kind of works, but it feels a little weak. I've measured the existing one and attached pictures of the new one next the old one. Can you please let me know if you have a better match (no lip in the center portion) which I won't need to modify? I have 6 left I'd like to return/exchange if you have a better matching part for me. thanks for your help!

Hi Paul,
Thanks for the quick reply. Here are two closer up pictures with the balance and the shoes. There is a bracket that holds the end of the pulleys attached to the spring. The metal bracket is what is interfering with the plastic part. I shot a quick video file, but its 98Mb so I sent you these pictures first. If it helps I can FTP or share the video file with you via YouTube or something.
Thanks
Dennis