Hi, not familiar with your coach at all or your specific part, but if your Dealer or Manufacturer cannot supply the needed part you could try part suppliers similar to the attached link (I don’t know if this specific one is good or bad to deal with) or failing that, the RV salvage yards. You can find them by Web searches. Good luck.
https://www.pellandent.com/RV-Window...-Knobs-Latches