Face Palm moment. check simple things first  

Face Palm moment. check simple things first

I had been printing PETG (Prusa brand clear) and after several good prints I had one sort of be reluctant to let go of the plate... I wiped it off with iso 99% and select the next item on the SD card.. the mesh routine runs and fails at the last point (point1) and I let it do its Z check and this starts repeating... i start checking things and trying again after I don't find a problem and of course the z check at point one also repeats.... rinse and repeat for about 15 min. 🙁

I at last notice that the PC plate is sitting on the right rear alignment pin.... and when the extruder is checking point1 that pin is hidden from where I sit... but that is just my excuse for not seeing it. 😳

I was not removing the plate on this series of prints and so i missed the way that the right rear was lifted by the pin. In any case when I got the mesh fail I should have removed the plate and checked for contamination and not finding any I would have put it back and the problem would have gone away (I was not removing the plate between plates as I was flexing it with it just tilted up to ge part release from the still warm plate on the last part I had needed to do a bit of side flex to get the part to pop off and this was when the plate got hung up (unnoticed) on that alignment pin...

So the key here is to think a bit before you dive into looking at everything and trying again... in this case the failure was at point one and it was a z calibration fail... the first thing I should have checked was that the plate was flush down on the heater. this would be more likely to be something between the PC plate and the heat bed and not what it was (the pin catching that plate) but checking for contamination Would have cleared the problem and saved me about 20 min of head scratching. 🙄