gdunham Well I kind of hate it when it's assumed I don't know what I am talking about.
Sorry that you couldn't get a straight answer from ZWO, but if you are used to these forums, that is pretty much the type of answer to expect.
As to your question, I suspect it is not so much a loose sensor, but possibly a loose printed circuit board that the sensor is attached to. (See my comments about loose tilt plate towards the end of this post too.)
This document that I found does not address the ASI2600, but it could be similar to the instructions for the ASI071, where you first remove the already familiar tilt plate (:-o) and then remove the cover that has the dust protection window.
https://astronomy-imaging-camera.com/manuals/How_to_clean_ASI_camera_and_redry_the_desiccant.pdf
You should then see the 4 screws that holds the printed circuit board down to the metal body. Heck, they might just need some lock washers.
The problem that I see is that you need a really clean and dry room when you open up the sensor chamber; otherwise you might end up with worse headaches with dust and dew later. You would at the minimum need to heat the desiccant before replacing them and sealing the camera back up again to maintain a dry camera chamber.
It is a real pain just to inspect the tightness of the screws; but you don't have too many other choices at this point.
The alternative is to see if your dealer will exchange the camera (since it is only 3 months old) and let them deal with the RMA nonsense with ZWO.
You might be able to get an RMA from ZWO to send the camera back to be fixed, but ZWO's QA is so abysmal, you might end up with a camera in worse condition when you get it back. Be ready to deal with all sorts of roadblocks that they will place in your way before they will even issue an RMA, and be prepared to pay for shipping, even though this is a quality issue with their camera.
Before doing any of that, you might also want to try to hold the tilt plate more securely by adding the missing "push" grub screws.
All of my recent ZWO cameras came with only one "push" screw per "pull" screw, while there is a second threaded hole for a second "push" screw. If you do not use a filter wheel or filter tray, you could use longer hex headed stainless steel screws too for now and then replace with a grub screw later with a little of the non-permanent Loctites.
Another thing I would try before anything else is to go back to a fully seated tilt plate -- you will of course end up with the tilt that you have seen before adjusting the tilt. But you should be able to check to see if the tilt changes with time/camera orientation, etc. If the tilt remains fixed, then the stability of the tilt plate is the culprit and the additional grub "push" screws might work.
Good luck,
Chen
EDIT: it just occurred to me that if it is loose sensor circuit board, then by tightening the circuit board, you may also get rid of the original tilt problem too; you may be able to use a fully seated tilt plate.
