Where to find and how to replace the infrared led array in the ring?

I did the same thing during disassembly while cleaning my Rift S controller joysticks. I ended up having to purchase a 10 pack of the correct IR SMD LEDs (part#:VSMB1940ITX01) and solder a new one in its place. Get in close with a camera and make sure there is still some solder pad remaining to stick it to before you take that project on. If you dare try this then get 10 of them. They are very small and pretty fragile so if your as unskilled as I am then your probably going to over heat the first 4 and crack them. I even cracked the 5th one a little on one corner but it still worked and has continued to for about a year now.