Does the hot shoe on your Sony a9 become loose and rattle when you attach a large flash? If so, Sony has acknowledged that this is an issue and is offering to repair it for free, providing your a9 is within the affected serial number range.
Here’s the statement that they have released:
In rare cases the Multi Interface Shoe on some ILCE-9 (α9) interchangeable lens digital cameras may rattle when an optional large flash unit is attached and high pressure is applied to it.
To address this issue, subject to the terms and conditions in the Limited Warranty that accompanied the Affected Cameras, we will repair your Affected Camera, free of charge, through March 31, 2020.
ILCE-9 cameras with serial numbers between 3370001 and 3381733 may be affected.
If your ILCE-9 is within the affected serial number range, and is experiencing this issue, we will repair your camera free of charge until March 31, 2020. Please contact Product Support for assistance.
For further details see:
It looks like my own recently purchased a9 is in the affected range 🙁 Although I don’t own a flash right now to test if it’s actually showing this issue.