Babyhawk II HD ( one that on arrival had a AIO fault, one motor not turning, that took three months to get a replacement board from EMax) Vista with FrSky R-XSR.

It is sometimes near smooth, very difficult to see any issue, and sometimes visibly judders in video slightly at a high frequency rate. Looks to be only in pitch. Probably if it were analog you'd not see an issue most of the time, but with HD, its there to be seen, no matter how small. Just occasionally you can also hear a motor noise that suggests vibration. No one particular throttle setting though and the judder is not worse when the noise is present.

Props are balanced. Props are aligned, no bent blades. differing sets of HQ and of original type EMax props used, no different.

Motors are smooth, no iffy bearings, no shafts bent, props are tight on motors (two screw and pin fixing, props right hole size to pin for location) Motors tight on frame  Motor screws well clear of windings. Motors usually sound clean apart from above. No Propwash issues.

PID/filter changes make no difference to judder.

Nebula Pro Camera is tight on its TPU mount to front posts.

Flies well, juddering or not.

I'm almost at a loss now as to what to try next, tempted to try a TPU mounting under the motors in case its frame harmonics.

What do you think?

Have any luck resolving this? I just got the Babyhawk II HD as my first digital drone and the camera vibration/judder is very noticeable when applying throttle above 50%. Noticed it on the maiden flight and I have not been able to find anything that would appear to be causing this.