Thanks for clearly sharing what the problem you had was, how you fixed it, and for both orally explaining using well done video. No one seemed to have a picture of what the blower filter looked like (mine was missing).

Where did you get that check valve?

I just found the air blower leaking water out the inlet pipe on my hot tub (same manufacturer, different model). Looks to be the same problem you had. Did you ever find the original location of the check valve on yours? I was thinking I'd replace the original one, but didn't consider just installing a new one down line until I saw this.