Replaced motor on Airsense 10, airflow still low

Hi, all. I have a 10-year-old Airsense 10, which was giving me a warning that the motor was reaching its end of life, so I replaced it with an Airsense 11. The airflow in the 11 is a lot better than my 10, so it seems like the motor was indeed going bad.

Next, I bought a replacement motor off Amazon so I could use the 10 as a backup/travel unit. I made the replacement using the guide on iFixit. Afterwards, the 10 is blowing better, but not as good as the 11 on the same pressure setting. Did I miss something, or did I get a bad motor?