My MG Buster Gundam kit had a broken "I1" part. Luckily it was a symmetrical piece, so I was able to model a replacement part in Fusion360.
3D Print on Mars Elegoo. Free download on sketchfab.com/nateordie if you need the part. Might need some glue, but it should slot in place okay.
Vid Edit in AE
Free Download if you need the part.