Yaton will have it, and cheap, expect it to be scratched up though.Check yaton he has plenty spare astro parts.
I’ve purchased from their site and eBay 3-4 times no problemsI found this site but I've never bought anything from it.
https://videotronicsuk.com/spare-parts/sega-parts/instruction-cover-bracket.html
I found this site but I've never bought anything from it.
https://videotronicsuk.com/spare-parts/sega-parts/instruction-cover-bracket.html
Videotronics is Mo, pretty sure he’s a member here.I’ve purchased from their site and eBay 3-4 times no problems