Loud knocking noise

[chowsey_tp]

After an hour on the turbo tonight, fairly steady state, a loud knocking started.
It's not the cassette and appears to not even be in sync with the fly wheel.
I can spin it up with it knocking, stop pedalling and as the flywheel spins down, the loud knocking still occurs, so it's something internal.
Any ideas? I don't want to keep pedalling in case it'll do even more damage.
Video of the noise here:
https://youtu.be/Out48He9XFM
Help!!!!

[chowsey_tp]

And to confirm, it's not the freehub either, just removed that along with the cassette and the qr stuff, and spinning the flywheel by hand also makes the knocking happen, so it's deffo something internal.

[luthier1964]

I have the exact same problem. Mine knocks so much that I can feel it through the crank. Getting off the bike and turning the crank by hand and spinning down, the knocks are so violent the bike visible shakes. I need some help to solve this problem please.