I should mention that I have the new magnetic bed installed. This issue originated before I changed it out. My z-axis appears to be drifting random direction from print to print. My Z-Offset fluctuates between -2.00 and 3.00 mm seemingly at random throughout the week as I print items. I have to tune the Z-Offset every single time I print. On occasion, the same Z-Offset will work for a day or more. Then, without warning at the start of a print the nozzle tries to push through the bed and I have to adjust the z-offset by +0.5 to +1.0 mm to get a good first layer. Other times, the nozzle will be 1.0 mm or more away from the bed and I have to adjust the z-offset by -0.5 to -2.0 mm to get a good first layer.
I have checked the x-axis and it is level. A 20.0 mm calibration cube is printing at 20.0 ±0.05 mm (probably the accuracy of my micrometer).
I don’t see this as a z-axis calibration issue because of the cube. It looks like somehow, somewhere the machine is losing track of where it is in between prints. I have noticed that, quite often, when I power the machine up with the z-offset at 0.00 mm and put the nozzle on the bed, the z position is 3.0 to 3.1 mm pretty consistently. I am not sure how to even interpret that because of how the bed is leveled using the washers. The top of the washers should be 0.00 mm and the new removable bed surface should be a fraction of a mm above that.
Any troubleshooting ideas or help would be appreciated.