Grand Carrera RS36 (CAV5185.FC6237) Crown Part Needed

Hi Guys, I got my Grand Carrera RS36 (CAV5185.FC6237) I've been wanting for the longest time in the used market. Somehow I got a bit aggressive and stripped the crown and now it's not screwing down. Bought a crown on ebay which looked like a perfect match but local repair shop said it's not the right one. I can't seem to find the part for this and I'm avoiding Tag as they're quoting me some ridiculous price. Any lead appreciated.