I don’t know how much time you have to dedicate to it, but it doesn’t take too long, at least a lot less than 12 days (where is snapmaker support anyways).
If you want to go that route we can talk more.
In the meantime, troubleshooting which exact part is the cause is easiest when at least the X axis is removed if you suspect one but not both of the Z towers are experiencing a loose carriage or anything else that would cause Z wobble symptoms.
have you seen @sycto’s video where his bed goes up and down? what do you see? - YouTube, from his thread here: Why does an .2mm initial layer measure .4mm +? - #15 by scyto
That’s the type of wobble to check for in the carriages on all linear modules, a subtle wobble. It can sometimes be seen (in scyto’s case) under powered movement, and sometimes it’s easier to detect by firmly rocking the carriages front back and side side and seeing if there’s any discernible movement.
If it’s not that then we’re still at square one.
There have been so many issues with linear module carriages loosening up though, I’m highly suspicious that’s the problem.