My printer has taken to printing the first 5 or 6mm of print perfectly, then deciding to print wherever it feels like. Sometimes it seems like the print is just offset in the Y axis as you can see a diffuse model being formed as if it's just printing in the wrong place. Sometimes it just prints wherever it feels like.
I've seen the printer printing outside its build volume (in a border 20mm around the supposed maximum build surface of the printer) occasionally but it's got to the point where it's refusing to do anything higher than a few mm without losing it's positioning.
I've performed the encoder test which checks out and it seems happy with but this only tests the X Axis rather than all axes. I've checked belt tensions and have never heard the motors stall or noticed any belt slip.
Before I have the case off does anyone know whether the Y Axis is encoded?
I've considered options such as step loss but it seems to be a jump to a position rather than a gradual position drift. I've checked for model impacts (previously an issue with a badly positioned roller) but everything looks (and sounds) like it did new.
I assume also that there's an initiation and synchronisation between the heads firing and step position so wondered if this could be a problem.
The Printer has preventative maintenance performed on a weekly basis and struggling to see where it might be going wrong.