Mullion clip for a 25 yr old octagon wood windoe

This window mullion originally had clips that had a pin to put into belved edge of wood window but had an "extention" that would fit into the slot on 4 of the ends. I do not know the MFg of window or have any of the original clips to show you.

In the screenshot 2024 pic above it shows a clip I have tried but I need the clip to be at least 1 inch in depth so it can reach the slit in mullion with a 5/8 internal width.

Do you have a mullion clip that would fit my original window design or a plastic clip similar to screenshot picture that is at 5/8 wide interally with at least 1" in depth?

Thanks!