TAZ 5 Small prints getting knocked off bed at the same height each time

My prints are getting detached from the bed at exactly the same height, (tested with 2 marvin prints and 1 benchy print).
I’m not sure if it’s just usual adhesion problems because it happened at exactly the same layer each time.
I actually saw it happen with one of the marvin prints - everything fine, good solid base, then it looked like the nozzle pushed on the part and it popped off the bed.

The printer is rather new, but previous prints have turned out fine. These prints are the first ones after I changed the extruder idler block, after the stock one developed cracks.

See the big white spot on the bed? That’s air under your PEI sheet. That may be the issue right there, though you can raise bed temperature to compensate. Also check the Z axis leadscrews to make sure you don’t have a motor slipping. If those both seem fine then look at overextrusion as a possibility.

The white spot is actually a space between the heating element and the glass… not sure if this is normal but that sagging area goes away once it heats up.

I have been printing at 110. Will take a look at the Z leadscrews but i’m not sure that’s it. The prints literally pop off at the exact same line each time, and i’ve tried printing on different parts of the bed.

If it really is a gap between the glass and heat bed then you might think about getting a new heat bed assembly soon. You will have a real issue getting your prints to stay stuck to the bed.