Here’s what they said:
It sounds like the clicking noise you are hearing is an issue with the mixer coupler. This is the component that reaches up to grab the magnets on the mixer to drag it across the tank. We find that some printers will overextend the couplers and cause them to make this clicking noise. We have a way to resolve this in-field by having one of our technicians remote into the printer to apply a calibration fix.
I’m going to let them apply the fix, as soon as I confirm a few things (i.e. that it accounts for both noises, that it won’t make anything worse for other tanks, and whether there’s a way to do the field calibration locally instead of via the cloud).
I think @CarsonB1986 had a similar fix done and it helped (although he mentioned some less prominent clicking returned again later).
If I get a chance beforehand I might run a quick test print in a different tank, that I’ve used before, to confirm whether the sounds seem to be limited to this one.