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I am Pete, and I'll be happy to assist with your question today.
If you shift your foot pressure to the front or the rear of the pedal does the knocking sound get better or worse?
You can try adjusting the two nuts and ensure every part is securely attached and in place.
If that doesn't help, then there is a mechanical misalignment somewhere else and you will need to try and observe where exactly the clash is occurring.
Hi, just checking in on your question, do you need any further assistance?