Noisy gear box axis 4 and 5

Noisy gear box https://youtu.be/zYQW_xbZGUs

Hi all wondering if anyone had similar issue and help me out I’ve been stuck with this issue over a year

I've spoken to ABB in Adelaide Australia where I brought it I haven't used it as in production I'm still in commissioning sadly they came over to inspect it they said nothing wrong with the gear box which bit strange they said it should sound like that the IRB6600’s gear box sounds different to average robot but I'm fairly sure there's issue what I’ve check and tried

Changed to latest robotware I’ve tried down grading as well still no change

I did a warmup ran in auto for 20 minutes no change

Checked the gearbox oil level it’s correct

Checked to see if there’s any signs of motor or gear box change out or inspection but doesn’t look like if it’s been touched

I did notice when running in auto I don’t notice it so much in manual mode at very low speed it doesn’t make the sound

I’ve looked in the routine service and noticed as that axis 4, 5 are not ok as in the picture