Dear all, thanks for reading this thread and thanks for your help in advance! Much appreciated.

We have an old (20+ years?) Milgard French Swing Patio Door latch/lock that somehow recently it can not be locked (the "tongue" become really loose and can't hold/hook the lock). Here is a label on the French Door:

Here you can see that it's:

MFGR (Manufacturer): MIL-027-1

SERIES: 5621

MST: 10-0 x 8-0/b>

MVT: 61" x 94"

We also contacted Milgard Customer Support but they kept asking us for the Sales Order Number (https://www.milgard.com/how-to-guides/video/locating-your-milgard-sales-order-number for the video about how to locate it). We tried everywhere but just can't locate that Sales Order Number. I guess they thought that we were asking for warranty but we were simply asking for replacement part. Any idea where/how we might be able to get this part?

Here are some photos about the part that needs to be replaced (and its dimension, etc.). Thanks!