Replacing a balance shoe

I have received a replacement spring shoe from SWISCO that is the proper size and type for my broken original. I have also watched several videos of how to replace a balance shoe, all of which involve cutting with a knife a slot into one side would all be very straightforward because vinyl is easy to cut with a knife.

However, in my particular replacement window, there is a metal shoe track inside the vinyl framing. Thus, just cutting the vinyl may not create enough room for me to tilt in the new shoe unless I also cut the edge of the inside metal track.

I have not yet attempted to cut either the vine or the metal track. I am prepared to do so but would like your guidance first on dealing with the inside metal track, which is not shown in any of the videos I have found on line so far. Thank you.

Two photos of the metal shoe track inside the vinyl jamb jam are attached. Hard to see, but is the best I can do. I have already cut back some of the vinyl at the top of the jamb and now need to cut the metal track inside the vinyl too. I expect to use an oscillating multi-tool to make the metal cut.

I went ahead with the rest of the repair and came to realize that that inside track was not metal after all. It was a dark brown color and hard; looked like metal. It is clearly a separate piece of the window assembly and since it was inside the white vinyl exterior, I couldn't get a good feel of it. However, once I started to cut into it with my oscillating multi tool, I realized that it too was vinyl and could be cut just as easily with a box cutter. The whole job is now done. Another notch in the belt. I now understand how tilt-out replacement window balance spring mechanics work and can easily fix the next one that breaks or becomes disconnected. And there will definitely be another one. It is nice to know now of a place where I can get the parts. Thanks.