While it’s possible your machine is getting old, which would be indicative of it’s having 15K run hours, the fact remains that your machine isn’t treating your apnea very well. You say your getting about 9 events per hour; your therapy isn’t very effective. Likely one of two things: your therapy needs have changed or your machine needs to be adjusted to serve you better. Just guessing, it’s possibly both.
For reference, I have COPD and Complex Apnea. I typically have about 1 AHI with my ASV; 1 event per night for me. 5 AHI with a CPAP is medically treated.
So, how many run hours? What are your pressure settings? Which CPAP do you have (more detailed than ResMed AirSense, this is like saying Ford F150)?