2001 Milgard Window - Plastic Trim Replacement

These are the original windows in my house that was built in about 2001. They are stamped with Milgard, but I haven't located a model name or number. The piece in the photo is a plastic trim piece that fits between the pane of glass and the frame. I can't get this to seat back into the slot. I'm hoping a new piece of trim will be more pliable. Let me know if I need to get a better picture - maybe in the daylight. Can you help me identify a replacement?