I think the special one that is 3D printed by RR forum member
@jonwienke aka "Uniden Scanner Mods and Accessories" is not taking new orders/repairs at this time.
I think some forum members have had luck asking for the part from Uniden and I do see that there are some options on eBay as well but I can't attest to these. In a pinch, I think someone here on RR was able to fashion a binder clip to work as well.