Excellent point. I wondered the same when I had everything apart. My only data point in this area is that - when I had things pulled apart - I could spin both fan blades quite easily by hand (I did not feel a bunch of resistance). Not that this means a lot, but it’s something.
This could also potentially explain the “mixed bag” verdict on these modules. If half of people using them are actually treating a symptom (vs the module being the actual problem), then it’s easily imaginable the mixed review they receive.
Nonetheless, I have ordered a Gates module (FCM108) and we’ll see how that goes when it gets here. I’m pretty well committed to fixing this and will be sure to update this thread at some point in the future, to help anyone else in the same spot.
Thanks for everyone’s assistance!