I have a UM3E which I've installed some buildtak print sheets on. I've turned off automatic leveling, as the nozzle would melt the print surface. This was behaving correctly for a long time, but recently it's started to misbehave.
At print starts it will drive the Z axis down past the end stop. Since it's lost its Z position it will then drive the nozzle into the bed.
When I turn on autoleveling and switch to a different bed material the startup sequence is a little different and it behaves normally.
I'd like to go back to buildtak sheets. They worked before.
Has anyone run into similar problems before? Any suggestions on fixes?