http://www.planetarypinball.com/mm5/merchant.mvc?Screen=PROD&Product_Code=CR-A11139&Category_Code=GS-1000 This should include the piece you're looking for
also available at marcos (my vendor of choice) https://www.marcospecialties.com/pinball-parts/A-11139.
Sadly I kinda don't think any of these guys are open right now so if you need one quick, finding one from person to person might be your only choice. I don't have a spare otherwise I'd be happy to help